ef30ab837c
* asan.c (create_cond_insert_point): Do not update edge count. * auto-profile.c (afdo_propagate_edge): Update for edge count removal. (afdo_propagate_circuit): Likewise. (afdo_calculate_branch_prob): Likewise. (afdo_annotate_cfg): Likewise. * basic-block.h (struct edge_def): Remove count. (edge_def::count): New accessor. * bb-reorder.c (rotate_loop): Update. (find_traces_1_round): Update. (connect_traces): Update. (sanitize_hot_paths): Update. * cfg.c (unchecked_make_edge): Update. (make_single_succ_edge): Update. (check_bb_profile): Update. (dump_edge_info): Update. (update_bb_profile_for_threading): Update. (scale_bbs_frequencies_int): Update. (scale_bbs_frequencies_gcov_type): Update. (scale_bbs_frequencies_profile_count): Update. (scale_bbs_frequencies): Update. * cfganal.c (connect_infinite_loops_to_exit): Update. * cfgbuild.c (compute_outgoing_frequencies): Update. (find_many_sub_basic_blocks): Update. * cfgcleanup.c (try_forward_edges): Update. (try_crossjump_to_edge): Update * cfgexpand.c (expand_gimple_cond): Update (expand_gimple_tailcall): Update (construct_exit_block): Update * cfghooks.c (verify_flow_info): Update (redirect_edge_succ_nodup): Update (split_edge): Update (make_forwarder_block): Update (duplicate_block): Update (account_profile_record): Update * cfgloop.c (find_subloop_latch_edge_by_profile): Update. * cfgloopanal.c (expected_loop_iterations_unbounded): Update. * cfgloopmanip.c (scale_loop_profile): Update. (loopify): Update. (lv_adjust_loop_entry_edge): Update. * cfgrtl.c (try_redirect_by_replacing_jump): Update. (force_nonfallthru_and_redirect): Update. (purge_dead_edges): Update. (rtl_flow_call_edges_add): Update. * cgraphunit.c (init_lowered_empty_function): Update. (cgraph_node::expand_thunk): Update. * gimple-pretty-print.c (dump_probability): Update. (dump_edge_probability): Update. * gimple-ssa-isolate-paths.c (isolate_path): Update. * haifa-sched.c (sched_create_recovery_edges): Update. * hsa-gen.c (convert_switch_statements): Update. * ifcvt.c (dead_or_predicable): Update. * ipa-inline-transform.c (inline_transform): Update. * ipa-split.c (split_function): Update. * ipa-utils.c (ipa_merge_profiles): Update. * loop-doloop.c (add_test): Update. * loop-unroll.c (unroll_loop_runtime_iterations): Update. * lto-streamer-in.c (input_cfg): Update. (input_function): Update. * lto-streamer-out.c (output_cfg): Update. * modulo-sched.c (sms_schedule): Update. * postreload-gcse.c (eliminate_partially_redundant_load): Update. * predict.c (maybe_hot_edge_p): Update. (unlikely_executed_edge_p): Update. (probably_never_executed_edge_p): Update. (dump_prediction): Update. (drop_profile): Update. (propagate_unlikely_bbs_forward): Update. (determine_unlikely_bbs): Update. (force_edge_cold): Update. * profile.c (compute_branch_probabilities): Update. * reg-stack.c (better_edge): Update. * shrink-wrap.c (handle_simple_exit): Update. * tracer.c (better_p): Update. * trans-mem.c (expand_transaction): Update. (split_bb_make_tm_edge): Update. * tree-call-cdce.c: Update. * tree-cfg.c (gimple_find_sub_bbs): Update. (gimple_split_edge): Update. (gimple_duplicate_sese_region): Update. (gimple_duplicate_sese_tail): Update. (gimple_flow_call_edges_add): Update. (insert_cond_bb): Update. (execute_fixup_cfg): Update. * tree-cfgcleanup.c (cleanup_control_expr_graph): Update. * tree-complex.c (expand_complex_div_wide): Update. * tree-eh.c (lower_resx): Update. (unsplit_eh): Update. (cleanup_empty_eh_move_lp): Update. * tree-inline.c (copy_edges_for_bb): Update. (freqs_to_counts): Update. (copy_cfg_body): Update. * tree-ssa-dce.c (remove_dead_stmt): Update. * tree-ssa-ifcombine.c (update_profile_after_ifcombine): Update. * tree-ssa-loop-im.c (execute_sm_if_changed): Update. * tree-ssa-loop-ivcanon.c (remove_exits_and_undefined_stmts): Update. (unloop_loops): Update. * tree-ssa-loop-manip.c (tree_transform_and_unroll_loop): Update. * tree-ssa-loop-split.c (connect_loops): Update. (split_loop): Update. * tree-ssa-loop-unswitch.c (hoist_guard): Update. * tree-ssa-phionlycprop.c (propagate_rhs_into_lhs): Update. * tree-ssa-phiopt.c (replace_phi_edge_with_variable): Update. * tree-ssa-reassoc.c (branch_fixup): Update. * tree-ssa-tail-merge.c (replace_block_by): Update. * tree-ssa-threadupdate.c (remove_ctrl_stmt_and_useless_edges): Update. (compute_path_counts): Update. (update_profile): Update. (recompute_probabilities): Update. (update_joiner_offpath_counts): Update. (estimated_freqs_path): Update. (freqs_to_counts_path): Update. (clear_counts_path): Update. (ssa_fix_duplicate_block_edges): Update. (duplicate_thread_path): Update. * tree-switch-conversion.c (hoist_edge_and_branch_if_true): Update. (case_bit_test_cmp): Update. (collect_switch_conv_info): Update. (gen_inbound_check): Update. (do_jump_if_equal): Update. (emit_cmp_and_jump_insns): Update. * tree-tailcall.c (decrease_profile): Update. (eliminate_tail_call): Update. * tree-vect-loop-manip.c (slpeel_add_loop_guard): Update. (vect_do_peeling): Update. * tree-vect-loop.c (scale_profile_for_vect_loop): Update. * ubsan.c (ubsan_expand_null_ifn): Update. (ubsan_expand_ptr_ifn): Update. * value-prof.c (gimple_divmod_fixed_value): Update. (gimple_mod_pow2): Update. (gimple_mod_subtract): Update. (gimple_ic): Update. (gimple_stringop_fixed_value): Update. From-SVN: r253910
2822 lines
86 KiB
C
2822 lines
86 KiB
C
/* Lower GIMPLE_SWITCH expressions to something more efficient than
|
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a jump table.
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Copyright (C) 2006-2017 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
|
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Free Software Foundation; either version 3, or (at your option) any
|
||
later version.
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||
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GCC is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
||
for more details.
|
||
|
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You should have received a copy of the GNU General Public License
|
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along with GCC; see the file COPYING3. If not, write to the Free
|
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Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA. */
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/* This file handles the lowering of GIMPLE_SWITCH to an indexed
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load, or a series of bit-test-and-branch expressions. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "backend.h"
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#include "insn-codes.h"
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#include "rtl.h"
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#include "tree.h"
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#include "gimple.h"
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#include "cfghooks.h"
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#include "tree-pass.h"
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#include "ssa.h"
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#include "optabs-tree.h"
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#include "cgraph.h"
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#include "gimple-pretty-print.h"
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#include "params.h"
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#include "fold-const.h"
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#include "varasm.h"
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#include "stor-layout.h"
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#include "cfganal.h"
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#include "gimplify.h"
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||
#include "gimple-iterator.h"
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#include "gimplify-me.h"
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#include "tree-cfg.h"
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#include "cfgloop.h"
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#include "alloc-pool.h"
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#include "target.h"
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#include "tree-into-ssa.h"
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/* ??? For lang_hooks.types.type_for_mode, but is there a word_mode
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type in the GIMPLE type system that is language-independent? */
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#include "langhooks.h"
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||
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/* Maximum number of case bit tests.
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FIXME: This should be derived from PARAM_CASE_VALUES_THRESHOLD and
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targetm.case_values_threshold(), or be its own param. */
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#define MAX_CASE_BIT_TESTS 3
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/* Split the basic block at the statement pointed to by GSIP, and insert
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a branch to the target basic block of E_TRUE conditional on tree
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expression COND.
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It is assumed that there is already an edge from the to-be-split
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basic block to E_TRUE->dest block. This edge is removed, and the
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profile information on the edge is re-used for the new conditional
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jump.
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||
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The CFG is updated. The dominator tree will not be valid after
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this transformation, but the immediate dominators are updated if
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UPDATE_DOMINATORS is true.
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Returns the newly created basic block. */
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static basic_block
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hoist_edge_and_branch_if_true (gimple_stmt_iterator *gsip,
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tree cond, edge e_true,
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bool update_dominators)
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{
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tree tmp;
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gcond *cond_stmt;
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edge e_false;
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basic_block new_bb, split_bb = gsi_bb (*gsip);
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bool dominated_e_true = false;
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gcc_assert (e_true->src == split_bb);
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if (update_dominators
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&& get_immediate_dominator (CDI_DOMINATORS, e_true->dest) == split_bb)
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dominated_e_true = true;
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tmp = force_gimple_operand_gsi (gsip, cond, /*simple=*/true, NULL,
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/*before=*/true, GSI_SAME_STMT);
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cond_stmt = gimple_build_cond_from_tree (tmp, NULL_TREE, NULL_TREE);
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gsi_insert_before (gsip, cond_stmt, GSI_SAME_STMT);
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e_false = split_block (split_bb, cond_stmt);
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new_bb = e_false->dest;
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redirect_edge_pred (e_true, split_bb);
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e_true->flags &= ~EDGE_FALLTHRU;
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e_true->flags |= EDGE_TRUE_VALUE;
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e_false->flags &= ~EDGE_FALLTHRU;
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e_false->flags |= EDGE_FALSE_VALUE;
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e_false->probability = e_true->probability.invert ();
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new_bb->count = e_false->count ();
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if (update_dominators)
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{
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if (dominated_e_true)
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set_immediate_dominator (CDI_DOMINATORS, e_true->dest, split_bb);
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set_immediate_dominator (CDI_DOMINATORS, e_false->dest, split_bb);
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}
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return new_bb;
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}
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/* Return true if a switch should be expanded as a bit test.
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RANGE is the difference between highest and lowest case.
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UNIQ is number of unique case node targets, not counting the default case.
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COUNT is the number of comparisons needed, not counting the default case. */
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static bool
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expand_switch_using_bit_tests_p (tree range,
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unsigned int uniq,
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unsigned int count, bool speed_p)
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{
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return (((uniq == 1 && count >= 3)
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|| (uniq == 2 && count >= 5)
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|| (uniq == 3 && count >= 6))
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&& lshift_cheap_p (speed_p)
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&& compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0
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&& compare_tree_int (range, 0) > 0);
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}
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/* Implement switch statements with bit tests
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A GIMPLE switch statement can be expanded to a short sequence of bit-wise
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comparisons. "switch(x)" is converted into "if ((1 << (x-MINVAL)) & CST)"
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where CST and MINVAL are integer constants. This is better than a series
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of compare-and-banch insns in some cases, e.g. we can implement:
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if ((x==4) || (x==6) || (x==9) || (x==11))
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as a single bit test:
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if ((1<<x) & ((1<<4)|(1<<6)|(1<<9)|(1<<11)))
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This transformation is only applied if the number of case targets is small,
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if CST constains at least 3 bits, and "1 << x" is cheap. The bit tests are
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performed in "word_mode".
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The following example shows the code the transformation generates:
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int bar(int x)
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{
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switch (x)
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{
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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case 'A': case 'B': case 'C': case 'D': case 'E':
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case 'F':
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return 1;
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}
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return 0;
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}
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==>
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bar (int x)
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{
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tmp1 = x - 48;
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if (tmp1 > (70 - 48)) goto L2;
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tmp2 = 1 << tmp1;
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tmp3 = 0b11111100000001111111111;
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if ((tmp2 & tmp3) != 0) goto L1 ; else goto L2;
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L1:
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return 1;
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L2:
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return 0;
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}
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TODO: There are still some improvements to this transformation that could
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be implemented:
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* A narrower mode than word_mode could be used if that is cheaper, e.g.
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for x86_64 where a narrower-mode shift may result in smaller code.
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* The compounded constant could be shifted rather than the one. The
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test would be either on the sign bit or on the least significant bit,
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depending on the direction of the shift. On some machines, the test
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for the branch would be free if the bit to test is already set by the
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shift operation.
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This transformation was contributed by Roger Sayle, see this e-mail:
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http://gcc.gnu.org/ml/gcc-patches/2003-01/msg01950.html
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*/
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/* A case_bit_test represents a set of case nodes that may be
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selected from using a bit-wise comparison. HI and LO hold
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the integer to be tested against, TARGET_EDGE contains the
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edge to the basic block to jump to upon success and BITS
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counts the number of case nodes handled by this test,
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typically the number of bits set in HI:LO. The LABEL field
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is used to quickly identify all cases in this set without
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looking at label_to_block for every case label. */
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struct case_bit_test
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{
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wide_int mask;
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edge target_edge;
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tree label;
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int bits;
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};
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/* Comparison function for qsort to order bit tests by decreasing
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probability of execution. Our best guess comes from a measured
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profile. If the profile counts are equal, break even on the
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number of case nodes, i.e. the node with the most cases gets
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tested first.
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TODO: Actually this currently runs before a profile is available.
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Therefore the case-as-bit-tests transformation should be done
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later in the pass pipeline, or something along the lines of
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"Efficient and effective branch reordering using profile data"
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(Yang et. al., 2002) should be implemented (although, how good
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is a paper is called "Efficient and effective ..." when the
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latter is implied by the former, but oh well...). */
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static int
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case_bit_test_cmp (const void *p1, const void *p2)
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{
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const struct case_bit_test *const d1 = (const struct case_bit_test *) p1;
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const struct case_bit_test *const d2 = (const struct case_bit_test *) p2;
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if (d2->target_edge->count () < d1->target_edge->count ())
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return -1;
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if (d2->target_edge->count () > d1->target_edge->count ())
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return 1;
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if (d2->bits != d1->bits)
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return d2->bits - d1->bits;
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/* Stabilize the sort. */
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return LABEL_DECL_UID (d2->label) - LABEL_DECL_UID (d1->label);
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}
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/* Expand a switch statement by a short sequence of bit-wise
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comparisons. "switch(x)" is effectively converted into
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"if ((1 << (x-MINVAL)) & CST)" where CST and MINVAL are
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integer constants.
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INDEX_EXPR is the value being switched on.
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MINVAL is the lowest case value of in the case nodes,
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and RANGE is highest value minus MINVAL. MINVAL and RANGE
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are not guaranteed to be of the same type as INDEX_EXPR
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(the gimplifier doesn't change the type of case label values,
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and MINVAL and RANGE are derived from those values).
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MAXVAL is MINVAL + RANGE.
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There *MUST* be MAX_CASE_BIT_TESTS or less unique case
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node targets. */
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static void
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emit_case_bit_tests (gswitch *swtch, tree index_expr,
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tree minval, tree range, tree maxval)
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{
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struct case_bit_test test[MAX_CASE_BIT_TESTS] = { {} };
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unsigned int i, j, k;
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unsigned int count;
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basic_block switch_bb = gimple_bb (swtch);
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basic_block default_bb, new_default_bb, new_bb;
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edge default_edge;
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bool update_dom = dom_info_available_p (CDI_DOMINATORS);
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vec<basic_block> bbs_to_fix_dom = vNULL;
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tree index_type = TREE_TYPE (index_expr);
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tree unsigned_index_type = unsigned_type_for (index_type);
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unsigned int branch_num = gimple_switch_num_labels (swtch);
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|
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gimple_stmt_iterator gsi;
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gassign *shift_stmt;
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|
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tree idx, tmp, csui;
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tree word_type_node = lang_hooks.types.type_for_mode (word_mode, 1);
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tree word_mode_zero = fold_convert (word_type_node, integer_zero_node);
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tree word_mode_one = fold_convert (word_type_node, integer_one_node);
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int prec = TYPE_PRECISION (word_type_node);
|
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wide_int wone = wi::one (prec);
|
||
|
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/* Get the edge for the default case. */
|
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tmp = gimple_switch_default_label (swtch);
|
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default_bb = label_to_block (CASE_LABEL (tmp));
|
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default_edge = find_edge (switch_bb, default_bb);
|
||
|
||
/* Go through all case labels, and collect the case labels, profile
|
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counts, and other information we need to build the branch tests. */
|
||
count = 0;
|
||
for (i = 1; i < branch_num; i++)
|
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{
|
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unsigned int lo, hi;
|
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tree cs = gimple_switch_label (swtch, i);
|
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tree label = CASE_LABEL (cs);
|
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edge e = find_edge (switch_bb, label_to_block (label));
|
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for (k = 0; k < count; k++)
|
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if (e == test[k].target_edge)
|
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break;
|
||
|
||
if (k == count)
|
||
{
|
||
gcc_checking_assert (count < MAX_CASE_BIT_TESTS);
|
||
test[k].mask = wi::zero (prec);
|
||
test[k].target_edge = e;
|
||
test[k].label = label;
|
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test[k].bits = 1;
|
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count++;
|
||
}
|
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else
|
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test[k].bits++;
|
||
|
||
lo = tree_to_uhwi (int_const_binop (MINUS_EXPR,
|
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CASE_LOW (cs), minval));
|
||
if (CASE_HIGH (cs) == NULL_TREE)
|
||
hi = lo;
|
||
else
|
||
hi = tree_to_uhwi (int_const_binop (MINUS_EXPR,
|
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CASE_HIGH (cs), minval));
|
||
|
||
for (j = lo; j <= hi; j++)
|
||
test[k].mask |= wi::lshift (wone, j);
|
||
}
|
||
|
||
qsort (test, count, sizeof (*test), case_bit_test_cmp);
|
||
|
||
/* If all values are in the 0 .. BITS_PER_WORD-1 range, we can get rid of
|
||
the minval subtractions, but it might make the mask constants more
|
||
expensive. So, compare the costs. */
|
||
if (compare_tree_int (minval, 0) > 0
|
||
&& compare_tree_int (maxval, GET_MODE_BITSIZE (word_mode)) < 0)
|
||
{
|
||
int cost_diff;
|
||
HOST_WIDE_INT m = tree_to_uhwi (minval);
|
||
rtx reg = gen_raw_REG (word_mode, 10000);
|
||
bool speed_p = optimize_bb_for_speed_p (gimple_bb (swtch));
|
||
cost_diff = set_rtx_cost (gen_rtx_PLUS (word_mode, reg,
|
||
GEN_INT (-m)), speed_p);
|
||
for (i = 0; i < count; i++)
|
||
{
|
||
rtx r = immed_wide_int_const (test[i].mask, word_mode);
|
||
cost_diff += set_src_cost (gen_rtx_AND (word_mode, reg, r),
|
||
word_mode, speed_p);
|
||
r = immed_wide_int_const (wi::lshift (test[i].mask, m), word_mode);
|
||
cost_diff -= set_src_cost (gen_rtx_AND (word_mode, reg, r),
|
||
word_mode, speed_p);
|
||
}
|
||
if (cost_diff > 0)
|
||
{
|
||
for (i = 0; i < count; i++)
|
||
test[i].mask = wi::lshift (test[i].mask, m);
|
||
minval = build_zero_cst (TREE_TYPE (minval));
|
||
range = maxval;
|
||
}
|
||
}
|
||
|
||
/* We generate two jumps to the default case label.
|
||
Split the default edge, so that we don't have to do any PHI node
|
||
updating. */
|
||
new_default_bb = split_edge (default_edge);
|
||
|
||
if (update_dom)
|
||
{
|
||
bbs_to_fix_dom.create (10);
|
||
bbs_to_fix_dom.quick_push (switch_bb);
|
||
bbs_to_fix_dom.quick_push (default_bb);
|
||
bbs_to_fix_dom.quick_push (new_default_bb);
|
||
}
|
||
|
||
/* Now build the test-and-branch code. */
|
||
|
||
gsi = gsi_last_bb (switch_bb);
|
||
|
||
/* idx = (unsigned)x - minval. */
|
||
idx = fold_convert (unsigned_index_type, index_expr);
|
||
idx = fold_build2 (MINUS_EXPR, unsigned_index_type, idx,
|
||
fold_convert (unsigned_index_type, minval));
|
||
idx = force_gimple_operand_gsi (&gsi, idx,
|
||
/*simple=*/true, NULL_TREE,
|
||
/*before=*/true, GSI_SAME_STMT);
|
||
|
||
/* if (idx > range) goto default */
|
||
range = force_gimple_operand_gsi (&gsi,
|
||
fold_convert (unsigned_index_type, range),
|
||
/*simple=*/true, NULL_TREE,
|
||
/*before=*/true, GSI_SAME_STMT);
|
||
tmp = fold_build2 (GT_EXPR, boolean_type_node, idx, range);
|
||
new_bb = hoist_edge_and_branch_if_true (&gsi, tmp, default_edge, update_dom);
|
||
if (update_dom)
|
||
bbs_to_fix_dom.quick_push (new_bb);
|
||
gcc_assert (gimple_bb (swtch) == new_bb);
|
||
gsi = gsi_last_bb (new_bb);
|
||
|
||
/* Any blocks dominated by the GIMPLE_SWITCH, but that are not successors
|
||
of NEW_BB, are still immediately dominated by SWITCH_BB. Make it so. */
|
||
if (update_dom)
|
||
{
|
||
vec<basic_block> dom_bbs;
|
||
basic_block dom_son;
|
||
|
||
dom_bbs = get_dominated_by (CDI_DOMINATORS, new_bb);
|
||
FOR_EACH_VEC_ELT (dom_bbs, i, dom_son)
|
||
{
|
||
edge e = find_edge (new_bb, dom_son);
|
||
if (e && single_pred_p (e->dest))
|
||
continue;
|
||
set_immediate_dominator (CDI_DOMINATORS, dom_son, switch_bb);
|
||
bbs_to_fix_dom.safe_push (dom_son);
|
||
}
|
||
dom_bbs.release ();
|
||
}
|
||
|
||
/* csui = (1 << (word_mode) idx) */
|
||
csui = make_ssa_name (word_type_node);
|
||
tmp = fold_build2 (LSHIFT_EXPR, word_type_node, word_mode_one,
|
||
fold_convert (word_type_node, idx));
|
||
tmp = force_gimple_operand_gsi (&gsi, tmp,
|
||
/*simple=*/false, NULL_TREE,
|
||
/*before=*/true, GSI_SAME_STMT);
|
||
shift_stmt = gimple_build_assign (csui, tmp);
|
||
gsi_insert_before (&gsi, shift_stmt, GSI_SAME_STMT);
|
||
update_stmt (shift_stmt);
|
||
|
||
/* for each unique set of cases:
|
||
if (const & csui) goto target */
|
||
for (k = 0; k < count; k++)
|
||
{
|
||
tmp = wide_int_to_tree (word_type_node, test[k].mask);
|
||
tmp = fold_build2 (BIT_AND_EXPR, word_type_node, csui, tmp);
|
||
tmp = force_gimple_operand_gsi (&gsi, tmp,
|
||
/*simple=*/true, NULL_TREE,
|
||
/*before=*/true, GSI_SAME_STMT);
|
||
tmp = fold_build2 (NE_EXPR, boolean_type_node, tmp, word_mode_zero);
|
||
new_bb = hoist_edge_and_branch_if_true (&gsi, tmp, test[k].target_edge,
|
||
update_dom);
|
||
if (update_dom)
|
||
bbs_to_fix_dom.safe_push (new_bb);
|
||
gcc_assert (gimple_bb (swtch) == new_bb);
|
||
gsi = gsi_last_bb (new_bb);
|
||
}
|
||
|
||
/* We should have removed all edges now. */
|
||
gcc_assert (EDGE_COUNT (gsi_bb (gsi)->succs) == 0);
|
||
|
||
/* If nothing matched, go to the default label. */
|
||
make_edge (gsi_bb (gsi), new_default_bb, EDGE_FALLTHRU);
|
||
|
||
/* The GIMPLE_SWITCH is now redundant. */
|
||
gsi_remove (&gsi, true);
|
||
|
||
if (update_dom)
|
||
{
|
||
/* Fix up the dominator tree. */
|
||
iterate_fix_dominators (CDI_DOMINATORS, bbs_to_fix_dom, true);
|
||
bbs_to_fix_dom.release ();
|
||
}
|
||
}
|
||
|
||
/*
|
||
Switch initialization conversion
|
||
|
||
The following pass changes simple initializations of scalars in a switch
|
||
statement into initializations from a static array. Obviously, the values
|
||
must be constant and known at compile time and a default branch must be
|
||
provided. For example, the following code:
|
||
|
||
int a,b;
|
||
|
||
switch (argc)
|
||
{
|
||
case 1:
|
||
case 2:
|
||
a_1 = 8;
|
||
b_1 = 6;
|
||
break;
|
||
case 3:
|
||
a_2 = 9;
|
||
b_2 = 5;
|
||
break;
|
||
case 12:
|
||
a_3 = 10;
|
||
b_3 = 4;
|
||
break;
|
||
default:
|
||
a_4 = 16;
|
||
b_4 = 1;
|
||
break;
|
||
}
|
||
a_5 = PHI <a_1, a_2, a_3, a_4>
|
||
b_5 = PHI <b_1, b_2, b_3, b_4>
|
||
|
||
|
||
is changed into:
|
||
|
||
static const int = CSWTCH01[] = {6, 6, 5, 1, 1, 1, 1, 1, 1, 1, 1, 4};
|
||
static const int = CSWTCH02[] = {8, 8, 9, 16, 16, 16, 16, 16, 16, 16,
|
||
16, 16, 10};
|
||
|
||
if (((unsigned) argc) - 1 < 11)
|
||
{
|
||
a_6 = CSWTCH02[argc - 1];
|
||
b_6 = CSWTCH01[argc - 1];
|
||
}
|
||
else
|
||
{
|
||
a_7 = 16;
|
||
b_7 = 1;
|
||
}
|
||
a_5 = PHI <a_6, a_7>
|
||
b_b = PHI <b_6, b_7>
|
||
|
||
There are further constraints. Specifically, the range of values across all
|
||
case labels must not be bigger than SWITCH_CONVERSION_BRANCH_RATIO (default
|
||
eight) times the number of the actual switch branches.
|
||
|
||
This transformation was contributed by Martin Jambor, see this e-mail:
|
||
http://gcc.gnu.org/ml/gcc-patches/2008-07/msg00011.html */
|
||
|
||
/* The main structure of the pass. */
|
||
struct switch_conv_info
|
||
{
|
||
/* The expression used to decide the switch branch. */
|
||
tree index_expr;
|
||
|
||
/* The following integer constants store the minimum and maximum value
|
||
covered by the case labels. */
|
||
tree range_min;
|
||
tree range_max;
|
||
|
||
/* The difference between the above two numbers. Stored here because it
|
||
is used in all the conversion heuristics, as well as for some of the
|
||
transformation, and it is expensive to re-compute it all the time. */
|
||
tree range_size;
|
||
|
||
/* Basic block that contains the actual GIMPLE_SWITCH. */
|
||
basic_block switch_bb;
|
||
|
||
/* Basic block that is the target of the default case. */
|
||
basic_block default_bb;
|
||
|
||
/* The single successor block of all branches out of the GIMPLE_SWITCH,
|
||
if such a block exists. Otherwise NULL. */
|
||
basic_block final_bb;
|
||
|
||
/* The probability of the default edge in the replaced switch. */
|
||
profile_probability default_prob;
|
||
|
||
/* The count of the default edge in the replaced switch. */
|
||
profile_count default_count;
|
||
|
||
/* Combined count of all other (non-default) edges in the replaced switch. */
|
||
profile_count other_count;
|
||
|
||
/* Number of phi nodes in the final bb (that we'll be replacing). */
|
||
int phi_count;
|
||
|
||
/* Array of default values, in the same order as phi nodes. */
|
||
tree *default_values;
|
||
|
||
/* Constructors of new static arrays. */
|
||
vec<constructor_elt, va_gc> **constructors;
|
||
|
||
/* Array of ssa names that are initialized with a value from a new static
|
||
array. */
|
||
tree *target_inbound_names;
|
||
|
||
/* Array of ssa names that are initialized with the default value if the
|
||
switch expression is out of range. */
|
||
tree *target_outbound_names;
|
||
|
||
/* VOP SSA_NAME. */
|
||
tree target_vop;
|
||
|
||
/* The first load statement that loads a temporary from a new static array.
|
||
*/
|
||
gimple *arr_ref_first;
|
||
|
||
/* The last load statement that loads a temporary from a new static array. */
|
||
gimple *arr_ref_last;
|
||
|
||
/* String reason why the case wasn't a good candidate that is written to the
|
||
dump file, if there is one. */
|
||
const char *reason;
|
||
|
||
/* True if default case is not used for any value between range_min and
|
||
range_max inclusive. */
|
||
bool contiguous_range;
|
||
|
||
/* True if default case does not have the required shape for other case
|
||
labels. */
|
||
bool default_case_nonstandard;
|
||
|
||
/* Parameters for expand_switch_using_bit_tests. Should be computed
|
||
the same way as in expand_case. */
|
||
unsigned int uniq;
|
||
unsigned int count;
|
||
};
|
||
|
||
/* Collect information about GIMPLE_SWITCH statement SWTCH into INFO. */
|
||
|
||
static void
|
||
collect_switch_conv_info (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
unsigned int branch_num = gimple_switch_num_labels (swtch);
|
||
tree min_case, max_case;
|
||
unsigned int count, i;
|
||
edge e, e_default, e_first;
|
||
edge_iterator ei;
|
||
basic_block first;
|
||
|
||
memset (info, 0, sizeof (*info));
|
||
|
||
/* The gimplifier has already sorted the cases by CASE_LOW and ensured there
|
||
is a default label which is the first in the vector.
|
||
Collect the bits we can deduce from the CFG. */
|
||
info->index_expr = gimple_switch_index (swtch);
|
||
info->switch_bb = gimple_bb (swtch);
|
||
info->default_bb
|
||
= label_to_block (CASE_LABEL (gimple_switch_default_label (swtch)));
|
||
e_default = find_edge (info->switch_bb, info->default_bb);
|
||
info->default_prob = e_default->probability;
|
||
info->default_count = e_default->count ();
|
||
FOR_EACH_EDGE (e, ei, info->switch_bb->succs)
|
||
if (e != e_default)
|
||
info->other_count += e->count ();
|
||
|
||
/* Get upper and lower bounds of case values, and the covered range. */
|
||
min_case = gimple_switch_label (swtch, 1);
|
||
max_case = gimple_switch_label (swtch, branch_num - 1);
|
||
|
||
info->range_min = CASE_LOW (min_case);
|
||
if (CASE_HIGH (max_case) != NULL_TREE)
|
||
info->range_max = CASE_HIGH (max_case);
|
||
else
|
||
info->range_max = CASE_LOW (max_case);
|
||
|
||
info->contiguous_range = true;
|
||
tree last = CASE_HIGH (min_case) ? CASE_HIGH (min_case) : info->range_min;
|
||
for (i = 2; i < branch_num; i++)
|
||
{
|
||
tree elt = gimple_switch_label (swtch, i);
|
||
if (wi::to_wide (last) + 1 != wi::to_wide (CASE_LOW (elt)))
|
||
{
|
||
info->contiguous_range = false;
|
||
break;
|
||
}
|
||
last = CASE_HIGH (elt) ? CASE_HIGH (elt) : CASE_LOW (elt);
|
||
}
|
||
|
||
if (info->contiguous_range)
|
||
{
|
||
first = label_to_block (CASE_LABEL (gimple_switch_label (swtch, 1)));
|
||
e_first = find_edge (info->switch_bb, first);
|
||
}
|
||
else
|
||
{
|
||
first = info->default_bb;
|
||
e_first = e_default;
|
||
}
|
||
|
||
/* See if there is one common successor block for all branch
|
||
targets. If it exists, record it in FINAL_BB.
|
||
Start with the destination of the first non-default case
|
||
if the range is contiguous and default case otherwise as
|
||
guess or its destination in case it is a forwarder block. */
|
||
if (! single_pred_p (e_first->dest))
|
||
info->final_bb = e_first->dest;
|
||
else if (single_succ_p (e_first->dest)
|
||
&& ! single_pred_p (single_succ (e_first->dest)))
|
||
info->final_bb = single_succ (e_first->dest);
|
||
/* Require that all switch destinations are either that common
|
||
FINAL_BB or a forwarder to it, except for the default
|
||
case if contiguous range. */
|
||
if (info->final_bb)
|
||
FOR_EACH_EDGE (e, ei, info->switch_bb->succs)
|
||
{
|
||
if (e->dest == info->final_bb)
|
||
continue;
|
||
|
||
if (single_pred_p (e->dest)
|
||
&& single_succ_p (e->dest)
|
||
&& single_succ (e->dest) == info->final_bb)
|
||
continue;
|
||
|
||
if (e == e_default && info->contiguous_range)
|
||
{
|
||
info->default_case_nonstandard = true;
|
||
continue;
|
||
}
|
||
|
||
info->final_bb = NULL;
|
||
break;
|
||
}
|
||
|
||
info->range_size
|
||
= int_const_binop (MINUS_EXPR, info->range_max, info->range_min);
|
||
|
||
/* Get a count of the number of case labels. Single-valued case labels
|
||
simply count as one, but a case range counts double, since it may
|
||
require two compares if it gets lowered as a branching tree. */
|
||
count = 0;
|
||
for (i = 1; i < branch_num; i++)
|
||
{
|
||
tree elt = gimple_switch_label (swtch, i);
|
||
count++;
|
||
if (CASE_HIGH (elt)
|
||
&& ! tree_int_cst_equal (CASE_LOW (elt), CASE_HIGH (elt)))
|
||
count++;
|
||
}
|
||
info->count = count;
|
||
|
||
/* Get the number of unique non-default targets out of the GIMPLE_SWITCH
|
||
block. Assume a CFG cleanup would have already removed degenerate
|
||
switch statements, this allows us to just use EDGE_COUNT. */
|
||
info->uniq = EDGE_COUNT (gimple_bb (swtch)->succs) - 1;
|
||
}
|
||
|
||
/* Checks whether the range given by individual case statements of the SWTCH
|
||
switch statement isn't too big and whether the number of branches actually
|
||
satisfies the size of the new array. */
|
||
|
||
static bool
|
||
check_range (struct switch_conv_info *info)
|
||
{
|
||
gcc_assert (info->range_size);
|
||
if (!tree_fits_uhwi_p (info->range_size))
|
||
{
|
||
info->reason = "index range way too large or otherwise unusable";
|
||
return false;
|
||
}
|
||
|
||
if (tree_to_uhwi (info->range_size)
|
||
> ((unsigned) info->count * SWITCH_CONVERSION_BRANCH_RATIO))
|
||
{
|
||
info->reason = "the maximum range-branch ratio exceeded";
|
||
return false;
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
/* Checks whether all but the FINAL_BB basic blocks are empty. */
|
||
|
||
static bool
|
||
check_all_empty_except_final (struct switch_conv_info *info)
|
||
{
|
||
edge e, e_default = find_edge (info->switch_bb, info->default_bb);
|
||
edge_iterator ei;
|
||
|
||
FOR_EACH_EDGE (e, ei, info->switch_bb->succs)
|
||
{
|
||
if (e->dest == info->final_bb)
|
||
continue;
|
||
|
||
if (!empty_block_p (e->dest))
|
||
{
|
||
if (info->contiguous_range && e == e_default)
|
||
{
|
||
info->default_case_nonstandard = true;
|
||
continue;
|
||
}
|
||
|
||
info->reason = "bad case - a non-final BB not empty";
|
||
return false;
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
/* This function checks whether all required values in phi nodes in final_bb
|
||
are constants. Required values are those that correspond to a basic block
|
||
which is a part of the examined switch statement. It returns true if the
|
||
phi nodes are OK, otherwise false. */
|
||
|
||
static bool
|
||
check_final_bb (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
gphi_iterator gsi;
|
||
|
||
info->phi_count = 0;
|
||
for (gsi = gsi_start_phis (info->final_bb); !gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
unsigned int i;
|
||
|
||
if (virtual_operand_p (gimple_phi_result (phi)))
|
||
continue;
|
||
|
||
info->phi_count++;
|
||
|
||
for (i = 0; i < gimple_phi_num_args (phi); i++)
|
||
{
|
||
basic_block bb = gimple_phi_arg_edge (phi, i)->src;
|
||
|
||
if (bb == info->switch_bb
|
||
|| (single_pred_p (bb)
|
||
&& single_pred (bb) == info->switch_bb
|
||
&& (!info->default_case_nonstandard
|
||
|| empty_block_p (bb))))
|
||
{
|
||
tree reloc, val;
|
||
const char *reason = NULL;
|
||
|
||
val = gimple_phi_arg_def (phi, i);
|
||
if (!is_gimple_ip_invariant (val))
|
||
reason = "non-invariant value from a case";
|
||
else
|
||
{
|
||
reloc = initializer_constant_valid_p (val, TREE_TYPE (val));
|
||
if ((flag_pic && reloc != null_pointer_node)
|
||
|| (!flag_pic && reloc == NULL_TREE))
|
||
{
|
||
if (reloc)
|
||
reason
|
||
= "value from a case would need runtime relocations";
|
||
else
|
||
reason
|
||
= "value from a case is not a valid initializer";
|
||
}
|
||
}
|
||
if (reason)
|
||
{
|
||
/* For contiguous range, we can allow non-constant
|
||
or one that needs relocation, as long as it is
|
||
only reachable from the default case. */
|
||
if (bb == info->switch_bb)
|
||
bb = info->final_bb;
|
||
if (!info->contiguous_range || bb != info->default_bb)
|
||
{
|
||
info->reason = reason;
|
||
return false;
|
||
}
|
||
|
||
unsigned int branch_num = gimple_switch_num_labels (swtch);
|
||
for (unsigned int i = 1; i < branch_num; i++)
|
||
{
|
||
tree lab = CASE_LABEL (gimple_switch_label (swtch, i));
|
||
if (label_to_block (lab) == bb)
|
||
{
|
||
info->reason = reason;
|
||
return false;
|
||
}
|
||
}
|
||
info->default_case_nonstandard = true;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
/* The following function allocates default_values, target_{in,out}_names and
|
||
constructors arrays. The last one is also populated with pointers to
|
||
vectors that will become constructors of new arrays. */
|
||
|
||
static void
|
||
create_temp_arrays (struct switch_conv_info *info)
|
||
{
|
||
int i;
|
||
|
||
info->default_values = XCNEWVEC (tree, info->phi_count * 3);
|
||
/* ??? Macros do not support multi argument templates in their
|
||
argument list. We create a typedef to work around that problem. */
|
||
typedef vec<constructor_elt, va_gc> *vec_constructor_elt_gc;
|
||
info->constructors = XCNEWVEC (vec_constructor_elt_gc, info->phi_count);
|
||
info->target_inbound_names = info->default_values + info->phi_count;
|
||
info->target_outbound_names = info->target_inbound_names + info->phi_count;
|
||
for (i = 0; i < info->phi_count; i++)
|
||
vec_alloc (info->constructors[i], tree_to_uhwi (info->range_size) + 1);
|
||
}
|
||
|
||
/* Free the arrays created by create_temp_arrays(). The vectors that are
|
||
created by that function are not freed here, however, because they have
|
||
already become constructors and must be preserved. */
|
||
|
||
static void
|
||
free_temp_arrays (struct switch_conv_info *info)
|
||
{
|
||
XDELETEVEC (info->constructors);
|
||
XDELETEVEC (info->default_values);
|
||
}
|
||
|
||
/* Populate the array of default values in the order of phi nodes.
|
||
DEFAULT_CASE is the CASE_LABEL_EXPR for the default switch branch
|
||
if the range is non-contiguous or the default case has standard
|
||
structure, otherwise it is the first non-default case instead. */
|
||
|
||
static void
|
||
gather_default_values (tree default_case, struct switch_conv_info *info)
|
||
{
|
||
gphi_iterator gsi;
|
||
basic_block bb = label_to_block (CASE_LABEL (default_case));
|
||
edge e;
|
||
int i = 0;
|
||
|
||
gcc_assert (CASE_LOW (default_case) == NULL_TREE
|
||
|| info->default_case_nonstandard);
|
||
|
||
if (bb == info->final_bb)
|
||
e = find_edge (info->switch_bb, bb);
|
||
else
|
||
e = single_succ_edge (bb);
|
||
|
||
for (gsi = gsi_start_phis (info->final_bb); !gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
if (virtual_operand_p (gimple_phi_result (phi)))
|
||
continue;
|
||
tree val = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
||
gcc_assert (val);
|
||
info->default_values[i++] = val;
|
||
}
|
||
}
|
||
|
||
/* The following function populates the vectors in the constructors array with
|
||
future contents of the static arrays. The vectors are populated in the
|
||
order of phi nodes. SWTCH is the switch statement being converted. */
|
||
|
||
static void
|
||
build_constructors (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
unsigned i, branch_num = gimple_switch_num_labels (swtch);
|
||
tree pos = info->range_min;
|
||
tree pos_one = build_int_cst (TREE_TYPE (pos), 1);
|
||
|
||
for (i = 1; i < branch_num; i++)
|
||
{
|
||
tree cs = gimple_switch_label (swtch, i);
|
||
basic_block bb = label_to_block (CASE_LABEL (cs));
|
||
edge e;
|
||
tree high;
|
||
gphi_iterator gsi;
|
||
int j;
|
||
|
||
if (bb == info->final_bb)
|
||
e = find_edge (info->switch_bb, bb);
|
||
else
|
||
e = single_succ_edge (bb);
|
||
gcc_assert (e);
|
||
|
||
while (tree_int_cst_lt (pos, CASE_LOW (cs)))
|
||
{
|
||
int k;
|
||
gcc_assert (!info->contiguous_range);
|
||
for (k = 0; k < info->phi_count; k++)
|
||
{
|
||
constructor_elt elt;
|
||
|
||
elt.index = int_const_binop (MINUS_EXPR, pos, info->range_min);
|
||
elt.value
|
||
= unshare_expr_without_location (info->default_values[k]);
|
||
info->constructors[k]->quick_push (elt);
|
||
}
|
||
|
||
pos = int_const_binop (PLUS_EXPR, pos, pos_one);
|
||
}
|
||
gcc_assert (tree_int_cst_equal (pos, CASE_LOW (cs)));
|
||
|
||
j = 0;
|
||
if (CASE_HIGH (cs))
|
||
high = CASE_HIGH (cs);
|
||
else
|
||
high = CASE_LOW (cs);
|
||
for (gsi = gsi_start_phis (info->final_bb);
|
||
!gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
if (virtual_operand_p (gimple_phi_result (phi)))
|
||
continue;
|
||
tree val = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
||
tree low = CASE_LOW (cs);
|
||
pos = CASE_LOW (cs);
|
||
|
||
do
|
||
{
|
||
constructor_elt elt;
|
||
|
||
elt.index = int_const_binop (MINUS_EXPR, pos, info->range_min);
|
||
elt.value = unshare_expr_without_location (val);
|
||
info->constructors[j]->quick_push (elt);
|
||
|
||
pos = int_const_binop (PLUS_EXPR, pos, pos_one);
|
||
} while (!tree_int_cst_lt (high, pos)
|
||
&& tree_int_cst_lt (low, pos));
|
||
j++;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* If all values in the constructor vector are the same, return the value.
|
||
Otherwise return NULL_TREE. Not supposed to be called for empty
|
||
vectors. */
|
||
|
||
static tree
|
||
constructor_contains_same_values_p (vec<constructor_elt, va_gc> *vec)
|
||
{
|
||
unsigned int i;
|
||
tree prev = NULL_TREE;
|
||
constructor_elt *elt;
|
||
|
||
FOR_EACH_VEC_SAFE_ELT (vec, i, elt)
|
||
{
|
||
if (!prev)
|
||
prev = elt->value;
|
||
else if (!operand_equal_p (elt->value, prev, OEP_ONLY_CONST))
|
||
return NULL_TREE;
|
||
}
|
||
return prev;
|
||
}
|
||
|
||
/* Return type which should be used for array elements, either TYPE's
|
||
main variant or, for integral types, some smaller integral type
|
||
that can still hold all the constants. */
|
||
|
||
static tree
|
||
array_value_type (gswitch *swtch, tree type, int num,
|
||
struct switch_conv_info *info)
|
||
{
|
||
unsigned int i, len = vec_safe_length (info->constructors[num]);
|
||
constructor_elt *elt;
|
||
int sign = 0;
|
||
tree smaller_type;
|
||
|
||
/* Types with alignments greater than their size can reach here, e.g. out of
|
||
SRA. We couldn't use these as an array component type so get back to the
|
||
main variant first, which, for our purposes, is fine for other types as
|
||
well. */
|
||
|
||
type = TYPE_MAIN_VARIANT (type);
|
||
|
||
if (!INTEGRAL_TYPE_P (type))
|
||
return type;
|
||
|
||
scalar_int_mode type_mode = SCALAR_INT_TYPE_MODE (type);
|
||
scalar_int_mode mode = get_narrowest_mode (type_mode);
|
||
if (GET_MODE_SIZE (type_mode) <= GET_MODE_SIZE (mode))
|
||
return type;
|
||
|
||
if (len < (optimize_bb_for_size_p (gimple_bb (swtch)) ? 2 : 32))
|
||
return type;
|
||
|
||
FOR_EACH_VEC_SAFE_ELT (info->constructors[num], i, elt)
|
||
{
|
||
wide_int cst;
|
||
|
||
if (TREE_CODE (elt->value) != INTEGER_CST)
|
||
return type;
|
||
|
||
cst = wi::to_wide (elt->value);
|
||
while (1)
|
||
{
|
||
unsigned int prec = GET_MODE_BITSIZE (mode);
|
||
if (prec > HOST_BITS_PER_WIDE_INT)
|
||
return type;
|
||
|
||
if (sign >= 0 && cst == wi::zext (cst, prec))
|
||
{
|
||
if (sign == 0 && cst == wi::sext (cst, prec))
|
||
break;
|
||
sign = 1;
|
||
break;
|
||
}
|
||
if (sign <= 0 && cst == wi::sext (cst, prec))
|
||
{
|
||
sign = -1;
|
||
break;
|
||
}
|
||
|
||
if (sign == 1)
|
||
sign = 0;
|
||
|
||
if (!GET_MODE_WIDER_MODE (mode).exists (&mode)
|
||
|| GET_MODE_SIZE (mode) >= GET_MODE_SIZE (type_mode))
|
||
return type;
|
||
}
|
||
}
|
||
|
||
if (sign == 0)
|
||
sign = TYPE_UNSIGNED (type) ? 1 : -1;
|
||
smaller_type = lang_hooks.types.type_for_mode (mode, sign >= 0);
|
||
if (GET_MODE_SIZE (type_mode)
|
||
<= GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (smaller_type)))
|
||
return type;
|
||
|
||
return smaller_type;
|
||
}
|
||
|
||
/* Create an appropriate array type and declaration and assemble a static array
|
||
variable. Also create a load statement that initializes the variable in
|
||
question with a value from the static array. SWTCH is the switch statement
|
||
being converted, NUM is the index to arrays of constructors, default values
|
||
and target SSA names for this particular array. ARR_INDEX_TYPE is the type
|
||
of the index of the new array, PHI is the phi node of the final BB that
|
||
corresponds to the value that will be loaded from the created array. TIDX
|
||
is an ssa name of a temporary variable holding the index for loads from the
|
||
new array. */
|
||
|
||
static void
|
||
build_one_array (gswitch *swtch, int num, tree arr_index_type,
|
||
gphi *phi, tree tidx, struct switch_conv_info *info)
|
||
{
|
||
tree name, cst;
|
||
gimple *load;
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (swtch);
|
||
location_t loc = gimple_location (swtch);
|
||
|
||
gcc_assert (info->default_values[num]);
|
||
|
||
name = copy_ssa_name (PHI_RESULT (phi));
|
||
info->target_inbound_names[num] = name;
|
||
|
||
cst = constructor_contains_same_values_p (info->constructors[num]);
|
||
if (cst)
|
||
load = gimple_build_assign (name, cst);
|
||
else
|
||
{
|
||
tree array_type, ctor, decl, value_type, fetch, default_type;
|
||
|
||
default_type = TREE_TYPE (info->default_values[num]);
|
||
value_type = array_value_type (swtch, default_type, num, info);
|
||
array_type = build_array_type (value_type, arr_index_type);
|
||
if (default_type != value_type)
|
||
{
|
||
unsigned int i;
|
||
constructor_elt *elt;
|
||
|
||
FOR_EACH_VEC_SAFE_ELT (info->constructors[num], i, elt)
|
||
elt->value = fold_convert (value_type, elt->value);
|
||
}
|
||
ctor = build_constructor (array_type, info->constructors[num]);
|
||
TREE_CONSTANT (ctor) = true;
|
||
TREE_STATIC (ctor) = true;
|
||
|
||
decl = build_decl (loc, VAR_DECL, NULL_TREE, array_type);
|
||
TREE_STATIC (decl) = 1;
|
||
DECL_INITIAL (decl) = ctor;
|
||
|
||
DECL_NAME (decl) = create_tmp_var_name ("CSWTCH");
|
||
DECL_ARTIFICIAL (decl) = 1;
|
||
DECL_IGNORED_P (decl) = 1;
|
||
TREE_CONSTANT (decl) = 1;
|
||
TREE_READONLY (decl) = 1;
|
||
DECL_IGNORED_P (decl) = 1;
|
||
varpool_node::finalize_decl (decl);
|
||
|
||
fetch = build4 (ARRAY_REF, value_type, decl, tidx, NULL_TREE,
|
||
NULL_TREE);
|
||
if (default_type != value_type)
|
||
{
|
||
fetch = fold_convert (default_type, fetch);
|
||
fetch = force_gimple_operand_gsi (&gsi, fetch, true, NULL_TREE,
|
||
true, GSI_SAME_STMT);
|
||
}
|
||
load = gimple_build_assign (name, fetch);
|
||
}
|
||
|
||
gsi_insert_before (&gsi, load, GSI_SAME_STMT);
|
||
update_stmt (load);
|
||
info->arr_ref_last = load;
|
||
}
|
||
|
||
/* Builds and initializes static arrays initialized with values gathered from
|
||
the SWTCH switch statement. Also creates statements that load values from
|
||
them. */
|
||
|
||
static void
|
||
build_arrays (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
tree arr_index_type;
|
||
tree tidx, sub, utype;
|
||
gimple *stmt;
|
||
gimple_stmt_iterator gsi;
|
||
gphi_iterator gpi;
|
||
int i;
|
||
location_t loc = gimple_location (swtch);
|
||
|
||
gsi = gsi_for_stmt (swtch);
|
||
|
||
/* Make sure we do not generate arithmetics in a subrange. */
|
||
utype = TREE_TYPE (info->index_expr);
|
||
if (TREE_TYPE (utype))
|
||
utype = lang_hooks.types.type_for_mode (TYPE_MODE (TREE_TYPE (utype)), 1);
|
||
else
|
||
utype = lang_hooks.types.type_for_mode (TYPE_MODE (utype), 1);
|
||
|
||
arr_index_type = build_index_type (info->range_size);
|
||
tidx = make_ssa_name (utype);
|
||
sub = fold_build2_loc (loc, MINUS_EXPR, utype,
|
||
fold_convert_loc (loc, utype, info->index_expr),
|
||
fold_convert_loc (loc, utype, info->range_min));
|
||
sub = force_gimple_operand_gsi (&gsi, sub,
|
||
false, NULL, true, GSI_SAME_STMT);
|
||
stmt = gimple_build_assign (tidx, sub);
|
||
|
||
gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
|
||
update_stmt (stmt);
|
||
info->arr_ref_first = stmt;
|
||
|
||
for (gpi = gsi_start_phis (info->final_bb), i = 0;
|
||
!gsi_end_p (gpi); gsi_next (&gpi))
|
||
{
|
||
gphi *phi = gpi.phi ();
|
||
if (!virtual_operand_p (gimple_phi_result (phi)))
|
||
build_one_array (swtch, i++, arr_index_type, phi, tidx, info);
|
||
else
|
||
{
|
||
edge e;
|
||
edge_iterator ei;
|
||
FOR_EACH_EDGE (e, ei, info->switch_bb->succs)
|
||
{
|
||
if (e->dest == info->final_bb)
|
||
break;
|
||
if (!info->default_case_nonstandard
|
||
|| e->dest != info->default_bb)
|
||
{
|
||
e = single_succ_edge (e->dest);
|
||
break;
|
||
}
|
||
}
|
||
gcc_assert (e && e->dest == info->final_bb);
|
||
info->target_vop = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Generates and appropriately inserts loads of default values at the position
|
||
given by BSI. Returns the last inserted statement. */
|
||
|
||
static gassign *
|
||
gen_def_assigns (gimple_stmt_iterator *gsi, struct switch_conv_info *info)
|
||
{
|
||
int i;
|
||
gassign *assign = NULL;
|
||
|
||
for (i = 0; i < info->phi_count; i++)
|
||
{
|
||
tree name = copy_ssa_name (info->target_inbound_names[i]);
|
||
info->target_outbound_names[i] = name;
|
||
assign = gimple_build_assign (name, info->default_values[i]);
|
||
gsi_insert_before (gsi, assign, GSI_SAME_STMT);
|
||
update_stmt (assign);
|
||
}
|
||
return assign;
|
||
}
|
||
|
||
/* Deletes the unused bbs and edges that now contain the switch statement and
|
||
its empty branch bbs. BBD is the now dead BB containing the original switch
|
||
statement, FINAL is the last BB of the converted switch statement (in terms
|
||
of succession). */
|
||
|
||
static void
|
||
prune_bbs (basic_block bbd, basic_block final, basic_block default_bb)
|
||
{
|
||
edge_iterator ei;
|
||
edge e;
|
||
|
||
for (ei = ei_start (bbd->succs); (e = ei_safe_edge (ei)); )
|
||
{
|
||
basic_block bb;
|
||
bb = e->dest;
|
||
remove_edge (e);
|
||
if (bb != final && bb != default_bb)
|
||
delete_basic_block (bb);
|
||
}
|
||
delete_basic_block (bbd);
|
||
}
|
||
|
||
/* Add values to phi nodes in final_bb for the two new edges. E1F is the edge
|
||
from the basic block loading values from an array and E2F from the basic
|
||
block loading default values. BBF is the last switch basic block (see the
|
||
bbf description in the comment below). */
|
||
|
||
static void
|
||
fix_phi_nodes (edge e1f, edge e2f, basic_block bbf,
|
||
struct switch_conv_info *info)
|
||
{
|
||
gphi_iterator gsi;
|
||
int i;
|
||
|
||
for (gsi = gsi_start_phis (bbf), i = 0;
|
||
!gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
tree inbound, outbound;
|
||
if (virtual_operand_p (gimple_phi_result (phi)))
|
||
inbound = outbound = info->target_vop;
|
||
else
|
||
{
|
||
inbound = info->target_inbound_names[i];
|
||
outbound = info->target_outbound_names[i++];
|
||
}
|
||
add_phi_arg (phi, inbound, e1f, UNKNOWN_LOCATION);
|
||
if (!info->default_case_nonstandard)
|
||
add_phi_arg (phi, outbound, e2f, UNKNOWN_LOCATION);
|
||
}
|
||
}
|
||
|
||
/* Creates a check whether the switch expression value actually falls into the
|
||
range given by all the cases. If it does not, the temporaries are loaded
|
||
with default values instead. SWTCH is the switch statement being converted.
|
||
|
||
bb0 is the bb with the switch statement, however, we'll end it with a
|
||
condition instead.
|
||
|
||
bb1 is the bb to be used when the range check went ok. It is derived from
|
||
the switch BB
|
||
|
||
bb2 is the bb taken when the expression evaluated outside of the range
|
||
covered by the created arrays. It is populated by loads of default
|
||
values.
|
||
|
||
bbF is a fall through for both bb1 and bb2 and contains exactly what
|
||
originally followed the switch statement.
|
||
|
||
bbD contains the switch statement (in the end). It is unreachable but we
|
||
still need to strip off its edges.
|
||
*/
|
||
|
||
static void
|
||
gen_inbound_check (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
tree label_decl1 = create_artificial_label (UNKNOWN_LOCATION);
|
||
tree label_decl2 = create_artificial_label (UNKNOWN_LOCATION);
|
||
tree label_decl3 = create_artificial_label (UNKNOWN_LOCATION);
|
||
glabel *label1, *label2, *label3;
|
||
tree utype, tidx;
|
||
tree bound;
|
||
|
||
gcond *cond_stmt;
|
||
|
||
gassign *last_assign = NULL;
|
||
gimple_stmt_iterator gsi;
|
||
basic_block bb0, bb1, bb2, bbf, bbd;
|
||
edge e01 = NULL, e02, e21, e1d, e1f, e2f;
|
||
location_t loc = gimple_location (swtch);
|
||
|
||
gcc_assert (info->default_values);
|
||
|
||
bb0 = gimple_bb (swtch);
|
||
|
||
tidx = gimple_assign_lhs (info->arr_ref_first);
|
||
utype = TREE_TYPE (tidx);
|
||
|
||
/* (end of) block 0 */
|
||
gsi = gsi_for_stmt (info->arr_ref_first);
|
||
gsi_next (&gsi);
|
||
|
||
bound = fold_convert_loc (loc, utype, info->range_size);
|
||
cond_stmt = gimple_build_cond (LE_EXPR, tidx, bound, NULL_TREE, NULL_TREE);
|
||
gsi_insert_before (&gsi, cond_stmt, GSI_SAME_STMT);
|
||
update_stmt (cond_stmt);
|
||
|
||
/* block 2 */
|
||
if (!info->default_case_nonstandard)
|
||
{
|
||
label2 = gimple_build_label (label_decl2);
|
||
gsi_insert_before (&gsi, label2, GSI_SAME_STMT);
|
||
last_assign = gen_def_assigns (&gsi, info);
|
||
}
|
||
|
||
/* block 1 */
|
||
label1 = gimple_build_label (label_decl1);
|
||
gsi_insert_before (&gsi, label1, GSI_SAME_STMT);
|
||
|
||
/* block F */
|
||
gsi = gsi_start_bb (info->final_bb);
|
||
label3 = gimple_build_label (label_decl3);
|
||
gsi_insert_before (&gsi, label3, GSI_SAME_STMT);
|
||
|
||
/* cfg fix */
|
||
e02 = split_block (bb0, cond_stmt);
|
||
bb2 = e02->dest;
|
||
|
||
if (info->default_case_nonstandard)
|
||
{
|
||
bb1 = bb2;
|
||
bb2 = info->default_bb;
|
||
e01 = e02;
|
||
e01->flags = EDGE_TRUE_VALUE;
|
||
e02 = make_edge (bb0, bb2, EDGE_FALSE_VALUE);
|
||
edge e_default = find_edge (bb1, bb2);
|
||
for (gphi_iterator gsi = gsi_start_phis (bb2);
|
||
!gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
tree arg = PHI_ARG_DEF_FROM_EDGE (phi, e_default);
|
||
add_phi_arg (phi, arg, e02,
|
||
gimple_phi_arg_location_from_edge (phi, e_default));
|
||
}
|
||
/* Partially fix the dominator tree, if it is available. */
|
||
if (dom_info_available_p (CDI_DOMINATORS))
|
||
redirect_immediate_dominators (CDI_DOMINATORS, bb1, bb0);
|
||
}
|
||
else
|
||
{
|
||
e21 = split_block (bb2, last_assign);
|
||
bb1 = e21->dest;
|
||
remove_edge (e21);
|
||
}
|
||
|
||
e1d = split_block (bb1, info->arr_ref_last);
|
||
bbd = e1d->dest;
|
||
remove_edge (e1d);
|
||
|
||
/* flags and profiles of the edge for in-range values */
|
||
if (!info->default_case_nonstandard)
|
||
e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE);
|
||
e01->probability = info->default_prob.invert ();
|
||
|
||
/* flags and profiles of the edge taking care of out-of-range values */
|
||
e02->flags &= ~EDGE_FALLTHRU;
|
||
e02->flags |= EDGE_FALSE_VALUE;
|
||
e02->probability = info->default_prob;
|
||
|
||
bbf = info->final_bb;
|
||
|
||
e1f = make_edge (bb1, bbf, EDGE_FALLTHRU);
|
||
e1f->probability = profile_probability::always ();
|
||
|
||
if (info->default_case_nonstandard)
|
||
e2f = NULL;
|
||
else
|
||
{
|
||
e2f = make_edge (bb2, bbf, EDGE_FALLTHRU);
|
||
e2f->probability = profile_probability::always ();
|
||
}
|
||
|
||
/* frequencies of the new BBs */
|
||
bb1->frequency = EDGE_FREQUENCY (e01);
|
||
bb2->frequency = EDGE_FREQUENCY (e02);
|
||
if (!info->default_case_nonstandard)
|
||
bbf->frequency = EDGE_FREQUENCY (e1f) + EDGE_FREQUENCY (e2f);
|
||
|
||
/* Tidy blocks that have become unreachable. */
|
||
prune_bbs (bbd, info->final_bb,
|
||
info->default_case_nonstandard ? info->default_bb : NULL);
|
||
|
||
/* Fixup the PHI nodes in bbF. */
|
||
fix_phi_nodes (e1f, e2f, bbf, info);
|
||
|
||
/* Fix the dominator tree, if it is available. */
|
||
if (dom_info_available_p (CDI_DOMINATORS))
|
||
{
|
||
vec<basic_block> bbs_to_fix_dom;
|
||
|
||
set_immediate_dominator (CDI_DOMINATORS, bb1, bb0);
|
||
if (!info->default_case_nonstandard)
|
||
set_immediate_dominator (CDI_DOMINATORS, bb2, bb0);
|
||
if (! get_immediate_dominator (CDI_DOMINATORS, bbf))
|
||
/* If bbD was the immediate dominator ... */
|
||
set_immediate_dominator (CDI_DOMINATORS, bbf, bb0);
|
||
|
||
bbs_to_fix_dom.create (3 + (bb2 != bbf));
|
||
bbs_to_fix_dom.quick_push (bb0);
|
||
bbs_to_fix_dom.quick_push (bb1);
|
||
if (bb2 != bbf)
|
||
bbs_to_fix_dom.quick_push (bb2);
|
||
bbs_to_fix_dom.quick_push (bbf);
|
||
|
||
iterate_fix_dominators (CDI_DOMINATORS, bbs_to_fix_dom, true);
|
||
bbs_to_fix_dom.release ();
|
||
}
|
||
}
|
||
|
||
/* The following function is invoked on every switch statement (the current one
|
||
is given in SWTCH) and runs the individual phases of switch conversion on it
|
||
one after another until one fails or the conversion is completed.
|
||
Returns NULL on success, or a pointer to a string with the reason why the
|
||
conversion failed. */
|
||
|
||
static const char *
|
||
process_switch (gswitch *swtch)
|
||
{
|
||
struct switch_conv_info info;
|
||
|
||
/* Group case labels so that we get the right results from the heuristics
|
||
that decide on the code generation approach for this switch. */
|
||
group_case_labels_stmt (swtch);
|
||
|
||
/* If this switch is now a degenerate case with only a default label,
|
||
there is nothing left for us to do. */
|
||
if (gimple_switch_num_labels (swtch) < 2)
|
||
return "switch is a degenerate case";
|
||
|
||
collect_switch_conv_info (swtch, &info);
|
||
|
||
/* No error markers should reach here (they should be filtered out
|
||
during gimplification). */
|
||
gcc_checking_assert (TREE_TYPE (info.index_expr) != error_mark_node);
|
||
|
||
/* A switch on a constant should have been optimized in tree-cfg-cleanup. */
|
||
gcc_checking_assert (! TREE_CONSTANT (info.index_expr));
|
||
|
||
if (info.uniq <= MAX_CASE_BIT_TESTS)
|
||
{
|
||
if (expand_switch_using_bit_tests_p (info.range_size,
|
||
info.uniq, info.count,
|
||
optimize_bb_for_speed_p
|
||
(gimple_bb (swtch))))
|
||
{
|
||
if (dump_file)
|
||
fputs (" expanding as bit test is preferable\n", dump_file);
|
||
emit_case_bit_tests (swtch, info.index_expr, info.range_min,
|
||
info.range_size, info.range_max);
|
||
loops_state_set (LOOPS_NEED_FIXUP);
|
||
return NULL;
|
||
}
|
||
|
||
if (info.uniq <= 2)
|
||
/* This will be expanded as a decision tree in stmt.c:expand_case. */
|
||
return " expanding as jumps is preferable";
|
||
}
|
||
|
||
/* If there is no common successor, we cannot do the transformation. */
|
||
if (! info.final_bb)
|
||
return "no common successor to all case label target blocks found";
|
||
|
||
/* Check the case label values are within reasonable range: */
|
||
if (!check_range (&info))
|
||
{
|
||
gcc_assert (info.reason);
|
||
return info.reason;
|
||
}
|
||
|
||
/* For all the cases, see whether they are empty, the assignments they
|
||
represent constant and so on... */
|
||
if (! check_all_empty_except_final (&info))
|
||
{
|
||
gcc_assert (info.reason);
|
||
return info.reason;
|
||
}
|
||
if (!check_final_bb (swtch, &info))
|
||
{
|
||
gcc_assert (info.reason);
|
||
return info.reason;
|
||
}
|
||
|
||
/* At this point all checks have passed and we can proceed with the
|
||
transformation. */
|
||
|
||
create_temp_arrays (&info);
|
||
gather_default_values (info.default_case_nonstandard
|
||
? gimple_switch_label (swtch, 1)
|
||
: gimple_switch_default_label (swtch), &info);
|
||
build_constructors (swtch, &info);
|
||
|
||
build_arrays (swtch, &info); /* Build the static arrays and assignments. */
|
||
gen_inbound_check (swtch, &info); /* Build the bounds check. */
|
||
|
||
/* Cleanup: */
|
||
free_temp_arrays (&info);
|
||
return NULL;
|
||
}
|
||
|
||
/* The main function of the pass scans statements for switches and invokes
|
||
process_switch on them. */
|
||
|
||
namespace {
|
||
|
||
const pass_data pass_data_convert_switch =
|
||
{
|
||
GIMPLE_PASS, /* type */
|
||
"switchconv", /* name */
|
||
OPTGROUP_NONE, /* optinfo_flags */
|
||
TV_TREE_SWITCH_CONVERSION, /* tv_id */
|
||
( PROP_cfg | PROP_ssa ), /* properties_required */
|
||
0, /* properties_provided */
|
||
0, /* properties_destroyed */
|
||
0, /* todo_flags_start */
|
||
TODO_update_ssa, /* todo_flags_finish */
|
||
};
|
||
|
||
class pass_convert_switch : public gimple_opt_pass
|
||
{
|
||
public:
|
||
pass_convert_switch (gcc::context *ctxt)
|
||
: gimple_opt_pass (pass_data_convert_switch, ctxt)
|
||
{}
|
||
|
||
/* opt_pass methods: */
|
||
virtual bool gate (function *) { return flag_tree_switch_conversion != 0; }
|
||
virtual unsigned int execute (function *);
|
||
|
||
}; // class pass_convert_switch
|
||
|
||
unsigned int
|
||
pass_convert_switch::execute (function *fun)
|
||
{
|
||
basic_block bb;
|
||
|
||
FOR_EACH_BB_FN (bb, fun)
|
||
{
|
||
const char *failure_reason;
|
||
gimple *stmt = last_stmt (bb);
|
||
if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
|
||
{
|
||
if (dump_file)
|
||
{
|
||
expanded_location loc = expand_location (gimple_location (stmt));
|
||
|
||
fprintf (dump_file, "beginning to process the following "
|
||
"SWITCH statement (%s:%d) : ------- \n",
|
||
loc.file, loc.line);
|
||
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
|
||
putc ('\n', dump_file);
|
||
}
|
||
|
||
failure_reason = process_switch (as_a <gswitch *> (stmt));
|
||
if (! failure_reason)
|
||
{
|
||
if (dump_file)
|
||
{
|
||
fputs ("Switch converted\n", dump_file);
|
||
fputs ("--------------------------------\n", dump_file);
|
||
}
|
||
|
||
/* Make no effort to update the post-dominator tree. It is actually not
|
||
that hard for the transformations we have performed, but it is not
|
||
supported by iterate_fix_dominators. */
|
||
free_dominance_info (CDI_POST_DOMINATORS);
|
||
}
|
||
else
|
||
{
|
||
if (dump_file)
|
||
{
|
||
fputs ("Bailing out - ", dump_file);
|
||
fputs (failure_reason, dump_file);
|
||
fputs ("\n--------------------------------\n", dump_file);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
} // anon namespace
|
||
|
||
gimple_opt_pass *
|
||
make_pass_convert_switch (gcc::context *ctxt)
|
||
{
|
||
return new pass_convert_switch (ctxt);
|
||
}
|
||
|
||
struct case_node
|
||
{
|
||
case_node *left; /* Left son in binary tree. */
|
||
case_node *right; /* Right son in binary tree;
|
||
also node chain. */
|
||
case_node *parent; /* Parent of node in binary tree. */
|
||
tree low; /* Lowest index value for this label. */
|
||
tree high; /* Highest index value for this label. */
|
||
basic_block case_bb; /* Label to jump to when node matches. */
|
||
tree case_label; /* Label to jump to when node matches. */
|
||
profile_probability prob; /* Probability of taking this case. */
|
||
profile_probability subtree_prob; /* Probability of reaching subtree
|
||
rooted at this node. */
|
||
};
|
||
|
||
typedef case_node *case_node_ptr;
|
||
|
||
static basic_block emit_case_nodes (basic_block, tree, case_node_ptr,
|
||
basic_block, tree, profile_probability,
|
||
tree, hash_map<tree, tree> *);
|
||
static bool node_has_low_bound (case_node_ptr, tree);
|
||
static bool node_has_high_bound (case_node_ptr, tree);
|
||
static bool node_is_bounded (case_node_ptr, tree);
|
||
|
||
/* Return the smallest number of different values for which it is best to use a
|
||
jump-table instead of a tree of conditional branches. */
|
||
|
||
static unsigned int
|
||
case_values_threshold (void)
|
||
{
|
||
unsigned int threshold = PARAM_VALUE (PARAM_CASE_VALUES_THRESHOLD);
|
||
|
||
if (threshold == 0)
|
||
threshold = targetm.case_values_threshold ();
|
||
|
||
return threshold;
|
||
}
|
||
|
||
/* Reset the aux field of all outgoing edges of basic block BB. */
|
||
|
||
static inline void
|
||
reset_out_edges_aux (basic_block bb)
|
||
{
|
||
edge e;
|
||
edge_iterator ei;
|
||
FOR_EACH_EDGE (e, ei, bb->succs)
|
||
e->aux = (void *) 0;
|
||
}
|
||
|
||
/* Compute the number of case labels that correspond to each outgoing edge of
|
||
STMT. Record this information in the aux field of the edge. */
|
||
|
||
static inline void
|
||
compute_cases_per_edge (gswitch *stmt)
|
||
{
|
||
basic_block bb = gimple_bb (stmt);
|
||
reset_out_edges_aux (bb);
|
||
int ncases = gimple_switch_num_labels (stmt);
|
||
for (int i = ncases - 1; i >= 1; --i)
|
||
{
|
||
tree elt = gimple_switch_label (stmt, i);
|
||
tree lab = CASE_LABEL (elt);
|
||
basic_block case_bb = label_to_block_fn (cfun, lab);
|
||
edge case_edge = find_edge (bb, case_bb);
|
||
case_edge->aux = (void *) ((intptr_t) (case_edge->aux) + 1);
|
||
}
|
||
}
|
||
|
||
/* Do the insertion of a case label into case_list. The labels are
|
||
fed to us in descending order from the sorted vector of case labels used
|
||
in the tree part of the middle end. So the list we construct is
|
||
sorted in ascending order.
|
||
|
||
LABEL is the case label to be inserted. LOW and HIGH are the bounds
|
||
against which the index is compared to jump to LABEL and PROB is the
|
||
estimated probability LABEL is reached from the switch statement. */
|
||
|
||
static case_node *
|
||
add_case_node (case_node *head, tree low, tree high, basic_block case_bb,
|
||
tree case_label, profile_probability prob,
|
||
object_allocator<case_node> &case_node_pool)
|
||
{
|
||
case_node *r;
|
||
|
||
gcc_checking_assert (low);
|
||
gcc_checking_assert (high && (TREE_TYPE (low) == TREE_TYPE (high)));
|
||
|
||
/* Add this label to the chain. */
|
||
r = case_node_pool.allocate ();
|
||
r->low = low;
|
||
r->high = high;
|
||
r->case_bb = case_bb;
|
||
r->case_label = case_label;
|
||
r->parent = r->left = NULL;
|
||
r->prob = prob;
|
||
r->subtree_prob = prob;
|
||
r->right = head;
|
||
return r;
|
||
}
|
||
|
||
/* Dump ROOT, a list or tree of case nodes, to file. */
|
||
|
||
static void
|
||
dump_case_nodes (FILE *f, case_node *root, int indent_step, int indent_level)
|
||
{
|
||
if (root == 0)
|
||
return;
|
||
indent_level++;
|
||
|
||
dump_case_nodes (f, root->left, indent_step, indent_level);
|
||
|
||
fputs (";; ", f);
|
||
fprintf (f, "%*s", indent_step * indent_level, "");
|
||
print_dec (wi::to_wide (root->low), f, TYPE_SIGN (TREE_TYPE (root->low)));
|
||
if (!tree_int_cst_equal (root->low, root->high))
|
||
{
|
||
fprintf (f, " ... ");
|
||
print_dec (wi::to_wide (root->high), f,
|
||
TYPE_SIGN (TREE_TYPE (root->high)));
|
||
}
|
||
fputs ("\n", f);
|
||
|
||
dump_case_nodes (f, root->right, indent_step, indent_level);
|
||
}
|
||
|
||
/* Take an ordered list of case nodes
|
||
and transform them into a near optimal binary tree,
|
||
on the assumption that any target code selection value is as
|
||
likely as any other.
|
||
|
||
The transformation is performed by splitting the ordered
|
||
list into two equal sections plus a pivot. The parts are
|
||
then attached to the pivot as left and right branches. Each
|
||
branch is then transformed recursively. */
|
||
|
||
static void
|
||
balance_case_nodes (case_node_ptr *head, case_node_ptr parent)
|
||
{
|
||
case_node_ptr np;
|
||
|
||
np = *head;
|
||
if (np)
|
||
{
|
||
int i = 0;
|
||
int ranges = 0;
|
||
case_node_ptr *npp;
|
||
case_node_ptr left;
|
||
|
||
/* Count the number of entries on branch. Also count the ranges. */
|
||
|
||
while (np)
|
||
{
|
||
if (!tree_int_cst_equal (np->low, np->high))
|
||
ranges++;
|
||
|
||
i++;
|
||
np = np->right;
|
||
}
|
||
|
||
if (i > 2)
|
||
{
|
||
/* Split this list if it is long enough for that to help. */
|
||
npp = head;
|
||
left = *npp;
|
||
|
||
/* If there are just three nodes, split at the middle one. */
|
||
if (i == 3)
|
||
npp = &(*npp)->right;
|
||
else
|
||
{
|
||
/* Find the place in the list that bisects the list's total cost,
|
||
where ranges count as 2.
|
||
Here I gets half the total cost. */
|
||
i = (i + ranges + 1) / 2;
|
||
while (1)
|
||
{
|
||
/* Skip nodes while their cost does not reach that amount. */
|
||
if (!tree_int_cst_equal ((*npp)->low, (*npp)->high))
|
||
i--;
|
||
i--;
|
||
if (i <= 0)
|
||
break;
|
||
npp = &(*npp)->right;
|
||
}
|
||
}
|
||
*head = np = *npp;
|
||
*npp = 0;
|
||
np->parent = parent;
|
||
np->left = left;
|
||
|
||
/* Optimize each of the two split parts. */
|
||
balance_case_nodes (&np->left, np);
|
||
balance_case_nodes (&np->right, np);
|
||
np->subtree_prob = np->prob;
|
||
np->subtree_prob += np->left->subtree_prob;
|
||
np->subtree_prob += np->right->subtree_prob;
|
||
}
|
||
else
|
||
{
|
||
/* Else leave this branch as one level,
|
||
but fill in `parent' fields. */
|
||
np = *head;
|
||
np->parent = parent;
|
||
np->subtree_prob = np->prob;
|
||
for (; np->right; np = np->right)
|
||
{
|
||
np->right->parent = np;
|
||
(*head)->subtree_prob += np->right->subtree_prob;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Return true if a switch should be expanded as a decision tree.
|
||
RANGE is the difference between highest and lowest case.
|
||
UNIQ is number of unique case node targets, not counting the default case.
|
||
COUNT is the number of comparisons needed, not counting the default case. */
|
||
|
||
static bool
|
||
expand_switch_as_decision_tree_p (tree range,
|
||
unsigned int uniq ATTRIBUTE_UNUSED,
|
||
unsigned int count)
|
||
{
|
||
int max_ratio;
|
||
|
||
/* If neither casesi or tablejump is available, or flag_jump_tables
|
||
over-ruled us, we really have no choice. */
|
||
if (!targetm.have_casesi () && !targetm.have_tablejump ())
|
||
return true;
|
||
if (!flag_jump_tables)
|
||
return true;
|
||
#ifndef ASM_OUTPUT_ADDR_DIFF_ELT
|
||
if (flag_pic)
|
||
return true;
|
||
#endif
|
||
|
||
/* If the switch is relatively small such that the cost of one
|
||
indirect jump on the target are higher than the cost of a
|
||
decision tree, go with the decision tree.
|
||
|
||
If range of values is much bigger than number of values,
|
||
or if it is too large to represent in a HOST_WIDE_INT,
|
||
make a sequence of conditional branches instead of a dispatch.
|
||
|
||
The definition of "much bigger" depends on whether we are
|
||
optimizing for size or for speed. If the former, the maximum
|
||
ratio range/count = 3, because this was found to be the optimal
|
||
ratio for size on i686-pc-linux-gnu, see PR11823. The ratio
|
||
10 is much older, and was probably selected after an extensive
|
||
benchmarking investigation on numerous platforms. Or maybe it
|
||
just made sense to someone at some point in the history of GCC,
|
||
who knows... */
|
||
max_ratio = optimize_insn_for_size_p () ? 3 : 10;
|
||
if (count < case_values_threshold () || !tree_fits_uhwi_p (range)
|
||
|| compare_tree_int (range, max_ratio * count) > 0)
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
static void
|
||
fix_phi_operands_for_edge (edge e, hash_map<tree, tree> *phi_mapping)
|
||
{
|
||
basic_block bb = e->dest;
|
||
gphi_iterator gsi;
|
||
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
|
||
tree *definition = phi_mapping->get (gimple_phi_result (phi));
|
||
if (definition)
|
||
add_phi_arg (phi, *definition, e, UNKNOWN_LOCATION);
|
||
}
|
||
}
|
||
|
||
|
||
/* Add an unconditional jump to CASE_BB that happens in basic block BB. */
|
||
|
||
static void
|
||
emit_jump (basic_block bb, basic_block case_bb,
|
||
hash_map<tree, tree> *phi_mapping)
|
||
{
|
||
edge e = single_succ_edge (bb);
|
||
redirect_edge_succ (e, case_bb);
|
||
fix_phi_operands_for_edge (e, phi_mapping);
|
||
}
|
||
|
||
/* Generate a decision tree, switching on INDEX_EXPR and jumping to
|
||
one of the labels in CASE_LIST or to the DEFAULT_LABEL.
|
||
DEFAULT_PROB is the estimated probability that it jumps to
|
||
DEFAULT_LABEL.
|
||
|
||
We generate a binary decision tree to select the appropriate target
|
||
code. */
|
||
|
||
static void
|
||
emit_case_decision_tree (gswitch *s, tree index_expr, tree index_type,
|
||
case_node_ptr case_list, basic_block default_bb,
|
||
tree default_label, profile_probability default_prob,
|
||
hash_map<tree, tree> *phi_mapping)
|
||
{
|
||
balance_case_nodes (&case_list, NULL);
|
||
|
||
if (dump_file)
|
||
dump_function_to_file (current_function_decl, dump_file, dump_flags);
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
int indent_step = ceil_log2 (TYPE_PRECISION (index_type)) + 2;
|
||
fprintf (dump_file, ";; Expanding GIMPLE switch as decision tree:\n");
|
||
dump_case_nodes (dump_file, case_list, indent_step, 0);
|
||
}
|
||
|
||
basic_block bb = gimple_bb (s);
|
||
gimple_stmt_iterator gsi = gsi_last_bb (bb);
|
||
edge e;
|
||
if (gsi_end_p (gsi))
|
||
e = split_block_after_labels (bb);
|
||
else
|
||
{
|
||
gsi_prev (&gsi);
|
||
e = split_block (bb, gsi_stmt (gsi));
|
||
}
|
||
bb = split_edge (e);
|
||
|
||
bb = emit_case_nodes (bb, index_expr, case_list, default_bb, default_label,
|
||
default_prob, index_type, phi_mapping);
|
||
|
||
if (bb)
|
||
emit_jump (bb, default_bb, phi_mapping);
|
||
|
||
/* Remove all edges and do just an edge that will reach default_bb. */
|
||
gsi = gsi_last_bb (gimple_bb (s));
|
||
gsi_remove (&gsi, true);
|
||
}
|
||
|
||
static void
|
||
record_phi_operand_mapping (const vec<basic_block> bbs, basic_block switch_bb,
|
||
hash_map <tree, tree> *map)
|
||
{
|
||
/* Record all PHI nodes that have to be fixed after conversion. */
|
||
for (unsigned i = 0; i < bbs.length (); i++)
|
||
{
|
||
basic_block bb = bbs[i];
|
||
|
||
gphi_iterator gsi;
|
||
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
|
||
for (unsigned i = 0; i < gimple_phi_num_args (phi); i++)
|
||
{
|
||
basic_block phi_src_bb = gimple_phi_arg_edge (phi, i)->src;
|
||
if (phi_src_bb == switch_bb)
|
||
{
|
||
tree def = gimple_phi_arg_def (phi, i);
|
||
tree result = gimple_phi_result (phi);
|
||
map->put (result, def);
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Attempt to expand gimple switch STMT to a decision tree. */
|
||
|
||
static bool
|
||
try_switch_expansion (gswitch *stmt)
|
||
{
|
||
tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE;
|
||
basic_block default_bb;
|
||
unsigned int count, uniq;
|
||
int i;
|
||
int ncases = gimple_switch_num_labels (stmt);
|
||
tree index_expr = gimple_switch_index (stmt);
|
||
tree index_type = TREE_TYPE (index_expr);
|
||
tree elt;
|
||
basic_block bb = gimple_bb (stmt);
|
||
|
||
hash_map<tree, tree> phi_mapping;
|
||
auto_vec<basic_block> case_bbs;
|
||
|
||
/* A list of case labels; it is first built as a list and it may then
|
||
be rearranged into a nearly balanced binary tree. */
|
||
case_node *case_list = 0;
|
||
|
||
/* A pool for case nodes. */
|
||
object_allocator<case_node> case_node_pool ("struct case_node pool");
|
||
|
||
/* cleanup_tree_cfg removes all SWITCH_EXPR with their index
|
||
expressions being INTEGER_CST. */
|
||
gcc_assert (TREE_CODE (index_expr) != INTEGER_CST);
|
||
|
||
if (ncases == 1)
|
||
return false;
|
||
|
||
/* Find the default case target label. */
|
||
tree default_label = CASE_LABEL (gimple_switch_default_label (stmt));
|
||
default_bb = label_to_block_fn (cfun, default_label);
|
||
edge default_edge = find_edge (bb, default_bb);
|
||
profile_probability default_prob = default_edge->probability;
|
||
case_bbs.safe_push (default_bb);
|
||
|
||
/* Get upper and lower bounds of case values. */
|
||
elt = gimple_switch_label (stmt, 1);
|
||
minval = fold_convert (index_type, CASE_LOW (elt));
|
||
elt = gimple_switch_label (stmt, ncases - 1);
|
||
if (CASE_HIGH (elt))
|
||
maxval = fold_convert (index_type, CASE_HIGH (elt));
|
||
else
|
||
maxval = fold_convert (index_type, CASE_LOW (elt));
|
||
|
||
/* Compute span of values. */
|
||
range = fold_build2 (MINUS_EXPR, index_type, maxval, minval);
|
||
|
||
/* Listify the labels queue and gather some numbers to decide
|
||
how to expand this switch. */
|
||
uniq = 0;
|
||
count = 0;
|
||
hash_set<tree> seen_labels;
|
||
compute_cases_per_edge (stmt);
|
||
|
||
for (i = ncases - 1; i >= 1; --i)
|
||
{
|
||
elt = gimple_switch_label (stmt, i);
|
||
tree low = CASE_LOW (elt);
|
||
gcc_assert (low);
|
||
tree high = CASE_HIGH (elt);
|
||
gcc_assert (!high || tree_int_cst_lt (low, high));
|
||
tree lab = CASE_LABEL (elt);
|
||
|
||
/* Count the elements.
|
||
A range counts double, since it requires two compares. */
|
||
count++;
|
||
if (high)
|
||
count++;
|
||
|
||
/* If we have not seen this label yet, then increase the
|
||
number of unique case node targets seen. */
|
||
if (!seen_labels.add (lab))
|
||
uniq++;
|
||
|
||
/* The bounds on the case range, LOW and HIGH, have to be converted
|
||
to case's index type TYPE. Note that the original type of the
|
||
case index in the source code is usually "lost" during
|
||
gimplification due to type promotion, but the case labels retain the
|
||
original type. Make sure to drop overflow flags. */
|
||
low = fold_convert (index_type, low);
|
||
if (TREE_OVERFLOW (low))
|
||
low = wide_int_to_tree (index_type, wi::to_wide (low));
|
||
|
||
/* The canonical from of a case label in GIMPLE is that a simple case
|
||
has an empty CASE_HIGH. For the casesi and tablejump expanders,
|
||
the back ends want simple cases to have high == low. */
|
||
if (!high)
|
||
high = low;
|
||
high = fold_convert (index_type, high);
|
||
if (TREE_OVERFLOW (high))
|
||
high = wide_int_to_tree (index_type, wi::to_wide (high));
|
||
|
||
basic_block case_bb = label_to_block_fn (cfun, lab);
|
||
edge case_edge = find_edge (bb, case_bb);
|
||
case_list = add_case_node (
|
||
case_list, low, high, case_bb, lab,
|
||
case_edge->probability.apply_scale (1, (intptr_t) (case_edge->aux)),
|
||
case_node_pool);
|
||
|
||
case_bbs.safe_push (case_bb);
|
||
}
|
||
reset_out_edges_aux (bb);
|
||
record_phi_operand_mapping (case_bbs, bb, &phi_mapping);
|
||
|
||
/* cleanup_tree_cfg removes all SWITCH_EXPR with a single
|
||
destination, such as one with a default case only.
|
||
It also removes cases that are out of range for the switch
|
||
type, so we should never get a zero here. */
|
||
gcc_assert (count > 0);
|
||
|
||
/* Decide how to expand this switch.
|
||
The two options at this point are a dispatch table (casesi or
|
||
tablejump) or a decision tree. */
|
||
|
||
if (expand_switch_as_decision_tree_p (range, uniq, count))
|
||
{
|
||
emit_case_decision_tree (stmt, index_expr, index_type, case_list,
|
||
default_bb, default_label, default_prob,
|
||
&phi_mapping);
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
/* The main function of the pass scans statements for switches and invokes
|
||
process_switch on them. */
|
||
|
||
namespace {
|
||
|
||
const pass_data pass_data_lower_switch =
|
||
{
|
||
GIMPLE_PASS, /* type */
|
||
"switchlower", /* name */
|
||
OPTGROUP_NONE, /* optinfo_flags */
|
||
TV_TREE_SWITCH_LOWERING, /* tv_id */
|
||
( PROP_cfg | PROP_ssa ), /* properties_required */
|
||
0, /* properties_provided */
|
||
0, /* properties_destroyed */
|
||
0, /* todo_flags_start */
|
||
TODO_update_ssa | TODO_cleanup_cfg, /* todo_flags_finish */
|
||
};
|
||
|
||
class pass_lower_switch : public gimple_opt_pass
|
||
{
|
||
public:
|
||
pass_lower_switch (gcc::context *ctxt)
|
||
: gimple_opt_pass (pass_data_lower_switch, ctxt)
|
||
{}
|
||
|
||
/* opt_pass methods: */
|
||
virtual bool gate (function *) { return true; }
|
||
virtual unsigned int execute (function *);
|
||
|
||
}; // class pass_lower_switch
|
||
|
||
unsigned int
|
||
pass_lower_switch::execute (function *fun)
|
||
{
|
||
basic_block bb;
|
||
bool expanded = false;
|
||
|
||
FOR_EACH_BB_FN (bb, fun)
|
||
{
|
||
gimple *stmt = last_stmt (bb);
|
||
if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
|
||
{
|
||
if (dump_file)
|
||
{
|
||
expanded_location loc = expand_location (gimple_location (stmt));
|
||
|
||
fprintf (dump_file, "beginning to process the following "
|
||
"SWITCH statement (%s:%d) : ------- \n",
|
||
loc.file, loc.line);
|
||
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
|
||
putc ('\n', dump_file);
|
||
}
|
||
|
||
expanded |= try_switch_expansion (as_a<gswitch *> (stmt));
|
||
}
|
||
}
|
||
|
||
if (expanded)
|
||
{
|
||
free_dominance_info (CDI_DOMINATORS);
|
||
free_dominance_info (CDI_POST_DOMINATORS);
|
||
mark_virtual_operands_for_renaming (cfun);
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
} // anon namespace
|
||
|
||
gimple_opt_pass *
|
||
make_pass_lower_switch (gcc::context *ctxt)
|
||
{
|
||
return new pass_lower_switch (ctxt);
|
||
}
|
||
|
||
/* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE.
|
||
PROB is the probability of jumping to LABEL. */
|
||
static basic_block
|
||
do_jump_if_equal (basic_block bb, tree op0, tree op1, basic_block label_bb,
|
||
profile_probability prob, hash_map<tree, tree> *phi_mapping)
|
||
{
|
||
gcond *cond = gimple_build_cond (EQ_EXPR, op0, op1, NULL_TREE, NULL_TREE);
|
||
gimple_stmt_iterator gsi = gsi_last_bb (bb);
|
||
gsi_insert_before (&gsi, cond, GSI_SAME_STMT);
|
||
|
||
gcc_assert (single_succ_p (bb));
|
||
|
||
/* Make a new basic block where false branch will take place. */
|
||
edge false_edge = split_block (bb, cond);
|
||
false_edge->flags = EDGE_FALSE_VALUE;
|
||
false_edge->probability = prob.invert ();
|
||
|
||
edge true_edge = make_edge (bb, label_bb, EDGE_TRUE_VALUE);
|
||
fix_phi_operands_for_edge (true_edge, phi_mapping);
|
||
true_edge->probability = prob;
|
||
|
||
return false_edge->dest;
|
||
}
|
||
|
||
/* Generate code to compare X with Y so that the condition codes are
|
||
set and to jump to LABEL if the condition is true. If X is a
|
||
constant and Y is not a constant, then the comparison is swapped to
|
||
ensure that the comparison RTL has the canonical form.
|
||
|
||
UNSIGNEDP nonzero says that X and Y are unsigned; this matters if they
|
||
need to be widened. UNSIGNEDP is also used to select the proper
|
||
branch condition code.
|
||
|
||
If X and Y have mode BLKmode, then SIZE specifies the size of both X and Y.
|
||
|
||
MODE is the mode of the inputs (in case they are const_int).
|
||
|
||
COMPARISON is the rtl operator to compare with (EQ, NE, GT, etc.).
|
||
It will be potentially converted into an unsigned variant based on
|
||
UNSIGNEDP to select a proper jump instruction.
|
||
|
||
PROB is the probability of jumping to LABEL. */
|
||
|
||
static basic_block
|
||
emit_cmp_and_jump_insns (basic_block bb, tree op0, tree op1,
|
||
tree_code comparison, basic_block label_bb,
|
||
profile_probability prob,
|
||
hash_map<tree, tree> *phi_mapping)
|
||
{
|
||
gcond *cond = gimple_build_cond (comparison, op0, op1, NULL_TREE, NULL_TREE);
|
||
gimple_stmt_iterator gsi = gsi_last_bb (bb);
|
||
gsi_insert_after (&gsi, cond, GSI_NEW_STMT);
|
||
|
||
gcc_assert (single_succ_p (bb));
|
||
|
||
/* Make a new basic block where false branch will take place. */
|
||
edge false_edge = split_block (bb, cond);
|
||
false_edge->flags = EDGE_FALSE_VALUE;
|
||
false_edge->probability = prob.invert ();
|
||
|
||
edge true_edge = make_edge (bb, label_bb, EDGE_TRUE_VALUE);
|
||
fix_phi_operands_for_edge (true_edge, phi_mapping);
|
||
true_edge->probability = prob;
|
||
|
||
return false_edge->dest;
|
||
}
|
||
|
||
/* Computes the conditional probability of jumping to a target if the branch
|
||
instruction is executed.
|
||
TARGET_PROB is the estimated probability of jumping to a target relative
|
||
to some basic block BB.
|
||
BASE_PROB is the probability of reaching the branch instruction relative
|
||
to the same basic block BB. */
|
||
|
||
static inline profile_probability
|
||
conditional_probability (profile_probability target_prob,
|
||
profile_probability base_prob)
|
||
{
|
||
return target_prob / base_prob;
|
||
}
|
||
|
||
/* Emit step-by-step code to select a case for the value of INDEX.
|
||
The thus generated decision tree follows the form of the
|
||
case-node binary tree NODE, whose nodes represent test conditions.
|
||
INDEX_TYPE is the type of the index of the switch.
|
||
|
||
Care is taken to prune redundant tests from the decision tree
|
||
by detecting any boundary conditions already checked by
|
||
emitted rtx. (See node_has_high_bound, node_has_low_bound
|
||
and node_is_bounded, above.)
|
||
|
||
Where the test conditions can be shown to be redundant we emit
|
||
an unconditional jump to the target code. As a further
|
||
optimization, the subordinates of a tree node are examined to
|
||
check for bounded nodes. In this case conditional and/or
|
||
unconditional jumps as a result of the boundary check for the
|
||
current node are arranged to target the subordinates associated
|
||
code for out of bound conditions on the current node.
|
||
|
||
We can assume that when control reaches the code generated here,
|
||
the index value has already been compared with the parents
|
||
of this node, and determined to be on the same side of each parent
|
||
as this node is. Thus, if this node tests for the value 51,
|
||
and a parent tested for 52, we don't need to consider
|
||
the possibility of a value greater than 51. If another parent
|
||
tests for the value 50, then this node need not test anything. */
|
||
|
||
static basic_block
|
||
emit_case_nodes (basic_block bb, tree index, case_node_ptr node,
|
||
basic_block default_bb, tree default_label,
|
||
profile_probability default_prob, tree index_type,
|
||
hash_map<tree, tree> *phi_mapping)
|
||
{
|
||
/* If INDEX has an unsigned type, we must make unsigned branches. */
|
||
profile_probability probability;
|
||
profile_probability prob = node->prob, subtree_prob = node->subtree_prob;
|
||
|
||
/* See if our parents have already tested everything for us.
|
||
If they have, emit an unconditional jump for this node. */
|
||
if (node_is_bounded (node, index_type))
|
||
{
|
||
emit_jump (bb, node->case_bb, phi_mapping);
|
||
return NULL;
|
||
}
|
||
|
||
else if (tree_int_cst_equal (node->low, node->high))
|
||
{
|
||
probability = conditional_probability (prob, subtree_prob + default_prob);
|
||
/* Node is single valued. First see if the index expression matches
|
||
this node and then check our children, if any. */
|
||
bb = do_jump_if_equal (bb, index, node->low, node->case_bb, probability,
|
||
phi_mapping);
|
||
/* Since this case is taken at this point, reduce its weight from
|
||
subtree_weight. */
|
||
subtree_prob -= prob;
|
||
if (node->right != 0 && node->left != 0)
|
||
{
|
||
/* This node has children on both sides.
|
||
Dispatch to one side or the other
|
||
by comparing the index value with this node's value.
|
||
If one subtree is bounded, check that one first,
|
||
so we can avoid real branches in the tree. */
|
||
|
||
if (node_is_bounded (node->right, index_type))
|
||
{
|
||
probability
|
||
= conditional_probability (node->right->prob,
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR,
|
||
node->right->case_bb, probability,
|
||
phi_mapping);
|
||
bb = emit_case_nodes (bb, index, node->left, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
}
|
||
|
||
else if (node_is_bounded (node->left, index_type))
|
||
{
|
||
probability
|
||
= conditional_probability (node->left->prob,
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, LT_EXPR,
|
||
node->left->case_bb, probability,
|
||
phi_mapping);
|
||
bb = emit_case_nodes (bb, index, node->right, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
}
|
||
|
||
/* If both children are single-valued cases with no
|
||
children, finish up all the work. This way, we can save
|
||
one ordered comparison. */
|
||
else if (tree_int_cst_equal (node->right->low, node->right->high)
|
||
&& node->right->left == 0 && node->right->right == 0
|
||
&& tree_int_cst_equal (node->left->low, node->left->high)
|
||
&& node->left->left == 0 && node->left->right == 0)
|
||
{
|
||
/* Neither node is bounded. First distinguish the two sides;
|
||
then emit the code for one side at a time. */
|
||
|
||
/* See if the value matches what the right hand side
|
||
wants. */
|
||
probability
|
||
= conditional_probability (node->right->prob,
|
||
subtree_prob + default_prob);
|
||
bb = do_jump_if_equal (bb, index, node->right->low,
|
||
node->right->case_bb, probability,
|
||
phi_mapping);
|
||
|
||
/* See if the value matches what the left hand side
|
||
wants. */
|
||
probability
|
||
= conditional_probability (node->left->prob,
|
||
subtree_prob + default_prob);
|
||
bb = do_jump_if_equal (bb, index, node->left->low,
|
||
node->left->case_bb, probability,
|
||
phi_mapping);
|
||
}
|
||
|
||
else
|
||
{
|
||
/* Neither node is bounded. First distinguish the two sides;
|
||
then emit the code for one side at a time. */
|
||
|
||
basic_block test_bb = split_edge (single_succ_edge (bb));
|
||
redirect_edge_succ (single_pred_edge (test_bb),
|
||
single_succ_edge (bb)->dest);
|
||
|
||
/* The default label could be reached either through the right
|
||
subtree or the left subtree. Divide the probability
|
||
equally. */
|
||
probability
|
||
= conditional_probability (node->right->subtree_prob
|
||
+ default_prob.apply_scale (1, 2),
|
||
subtree_prob + default_prob);
|
||
/* See if the value is on the right. */
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR,
|
||
test_bb, probability, phi_mapping);
|
||
default_prob = default_prob.apply_scale (1, 2);
|
||
|
||
/* Value must be on the left.
|
||
Handle the left-hand subtree. */
|
||
bb = emit_case_nodes (bb, index, node->left, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
/* If left-hand subtree does nothing,
|
||
go to default. */
|
||
|
||
if (bb && default_bb)
|
||
emit_jump (bb, default_bb, phi_mapping);
|
||
|
||
/* Code branches here for the right-hand subtree. */
|
||
bb = emit_case_nodes (test_bb, index, node->right, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
}
|
||
}
|
||
else if (node->right != 0 && node->left == 0)
|
||
{
|
||
/* Here we have a right child but no left so we issue a conditional
|
||
branch to default and process the right child.
|
||
|
||
Omit the conditional branch to default if the right child
|
||
does not have any children and is single valued; it would
|
||
cost too much space to save so little time. */
|
||
|
||
if (node->right->right || node->right->left
|
||
|| !tree_int_cst_equal (node->right->low, node->right->high))
|
||
{
|
||
if (!node_has_low_bound (node, index_type))
|
||
{
|
||
probability
|
||
= conditional_probability (default_prob.apply_scale (1, 2),
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, LT_EXPR,
|
||
default_bb, probability,
|
||
phi_mapping);
|
||
default_prob = default_prob.apply_scale (1, 2);
|
||
}
|
||
|
||
bb = emit_case_nodes (bb, index, node->right, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
}
|
||
else
|
||
{
|
||
probability
|
||
= conditional_probability (node->right->subtree_prob,
|
||
subtree_prob + default_prob);
|
||
/* We cannot process node->right normally
|
||
since we haven't ruled out the numbers less than
|
||
this node's value. So handle node->right explicitly. */
|
||
bb = do_jump_if_equal (bb, index, node->right->low,
|
||
node->right->case_bb, probability,
|
||
phi_mapping);
|
||
}
|
||
}
|
||
|
||
else if (node->right == 0 && node->left != 0)
|
||
{
|
||
/* Just one subtree, on the left. */
|
||
if (node->left->left || node->left->right
|
||
|| !tree_int_cst_equal (node->left->low, node->left->high))
|
||
{
|
||
if (!node_has_high_bound (node, index_type))
|
||
{
|
||
probability
|
||
= conditional_probability (default_prob.apply_scale (1, 2),
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR,
|
||
default_bb, probability,
|
||
phi_mapping);
|
||
default_prob = default_prob.apply_scale (1, 2);
|
||
}
|
||
|
||
bb = emit_case_nodes (bb, index, node->left, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
}
|
||
else
|
||
{
|
||
probability
|
||
= conditional_probability (node->left->subtree_prob,
|
||
subtree_prob + default_prob);
|
||
/* We cannot process node->left normally
|
||
since we haven't ruled out the numbers less than
|
||
this node's value. So handle node->left explicitly. */
|
||
do_jump_if_equal (bb, index, node->left->low, node->left->case_bb,
|
||
probability, phi_mapping);
|
||
}
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* Node is a range. These cases are very similar to those for a single
|
||
value, except that we do not start by testing whether this node
|
||
is the one to branch to. */
|
||
|
||
if (node->right != 0 && node->left != 0)
|
||
{
|
||
/* Node has subtrees on both sides.
|
||
If the right-hand subtree is bounded,
|
||
test for it first, since we can go straight there.
|
||
Otherwise, we need to make a branch in the control structure,
|
||
then handle the two subtrees. */
|
||
basic_block test_bb = NULL;
|
||
|
||
if (node_is_bounded (node->right, index_type))
|
||
{
|
||
/* Right hand node is fully bounded so we can eliminate any
|
||
testing and branch directly to the target code. */
|
||
probability
|
||
= conditional_probability (node->right->subtree_prob,
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR,
|
||
node->right->case_bb, probability,
|
||
phi_mapping);
|
||
}
|
||
else
|
||
{
|
||
/* Right hand node requires testing.
|
||
Branch to a label where we will handle it later. */
|
||
|
||
test_bb = split_edge (single_succ_edge (bb));
|
||
redirect_edge_succ (single_pred_edge (test_bb),
|
||
single_succ_edge (bb)->dest);
|
||
|
||
probability
|
||
= conditional_probability (node->right->subtree_prob
|
||
+ default_prob.apply_scale (1, 2),
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR,
|
||
test_bb, probability, phi_mapping);
|
||
default_prob = default_prob.apply_scale (1, 2);
|
||
}
|
||
|
||
/* Value belongs to this node or to the left-hand subtree. */
|
||
|
||
probability
|
||
= conditional_probability (prob, subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->low, GE_EXPR,
|
||
node->case_bb, probability,
|
||
phi_mapping);
|
||
|
||
/* Handle the left-hand subtree. */
|
||
bb = emit_case_nodes (bb, index, node->left, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
|
||
/* If right node had to be handled later, do that now. */
|
||
if (test_bb)
|
||
{
|
||
/* If the left-hand subtree fell through,
|
||
don't let it fall into the right-hand subtree. */
|
||
if (bb && default_bb)
|
||
emit_jump (bb, default_bb, phi_mapping);
|
||
|
||
bb = emit_case_nodes (test_bb, index, node->right, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
}
|
||
}
|
||
|
||
else if (node->right != 0 && node->left == 0)
|
||
{
|
||
/* Deal with values to the left of this node,
|
||
if they are possible. */
|
||
if (!node_has_low_bound (node, index_type))
|
||
{
|
||
probability
|
||
= conditional_probability (default_prob.apply_scale (1, 2),
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->low, LT_EXPR,
|
||
default_bb, probability,
|
||
phi_mapping);
|
||
default_prob = default_prob.apply_scale (1, 2);
|
||
}
|
||
|
||
/* Value belongs to this node or to the right-hand subtree. */
|
||
|
||
probability
|
||
= conditional_probability (prob, subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, LE_EXPR,
|
||
node->case_bb, probability,
|
||
phi_mapping);
|
||
|
||
bb = emit_case_nodes (bb, index, node->right, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
}
|
||
|
||
else if (node->right == 0 && node->left != 0)
|
||
{
|
||
/* Deal with values to the right of this node,
|
||
if they are possible. */
|
||
if (!node_has_high_bound (node, index_type))
|
||
{
|
||
probability
|
||
= conditional_probability (default_prob.apply_scale (1, 2),
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR,
|
||
default_bb, probability,
|
||
phi_mapping);
|
||
default_prob = default_prob.apply_scale (1, 2);
|
||
}
|
||
|
||
/* Value belongs to this node or to the left-hand subtree. */
|
||
|
||
probability
|
||
= conditional_probability (prob, subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->low, GE_EXPR,
|
||
node->case_bb, probability,
|
||
phi_mapping);
|
||
|
||
bb = emit_case_nodes (bb, index, node->left, default_bb,
|
||
default_label, default_prob, index_type,
|
||
phi_mapping);
|
||
}
|
||
|
||
else
|
||
{
|
||
/* Node has no children so we check low and high bounds to remove
|
||
redundant tests. Only one of the bounds can exist,
|
||
since otherwise this node is bounded--a case tested already. */
|
||
bool high_bound = node_has_high_bound (node, index_type);
|
||
bool low_bound = node_has_low_bound (node, index_type);
|
||
|
||
if (!high_bound && low_bound)
|
||
{
|
||
probability
|
||
= conditional_probability (default_prob,
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR,
|
||
default_bb, probability,
|
||
phi_mapping);
|
||
}
|
||
|
||
else if (!low_bound && high_bound)
|
||
{
|
||
probability
|
||
= conditional_probability (default_prob,
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, index, node->low, LT_EXPR,
|
||
default_bb, probability,
|
||
phi_mapping);
|
||
}
|
||
else if (!low_bound && !high_bound)
|
||
{
|
||
tree lhs, rhs;
|
||
generate_range_test (bb, index, node->low, node->high,
|
||
&lhs, &rhs);
|
||
probability
|
||
= conditional_probability (default_prob,
|
||
subtree_prob + default_prob);
|
||
bb = emit_cmp_and_jump_insns (bb, lhs, rhs, GT_EXPR,
|
||
default_bb, probability,
|
||
phi_mapping);
|
||
}
|
||
|
||
emit_jump (bb, node->case_bb, phi_mapping);
|
||
return NULL;
|
||
}
|
||
}
|
||
|
||
return bb;
|
||
}
|
||
|
||
/* Search the parent sections of the case node tree
|
||
to see if a test for the lower bound of NODE would be redundant.
|
||
INDEX_TYPE is the type of the index expression.
|
||
|
||
The instructions to generate the case decision tree are
|
||
output in the same order as nodes are processed so it is
|
||
known that if a parent node checks the range of the current
|
||
node minus one that the current node is bounded at its lower
|
||
span. Thus the test would be redundant. */
|
||
|
||
static bool
|
||
node_has_low_bound (case_node_ptr node, tree index_type)
|
||
{
|
||
tree low_minus_one;
|
||
case_node_ptr pnode;
|
||
|
||
/* If the lower bound of this node is the lowest value in the index type,
|
||
we need not test it. */
|
||
|
||
if (tree_int_cst_equal (node->low, TYPE_MIN_VALUE (index_type)))
|
||
return true;
|
||
|
||
/* If this node has a left branch, the value at the left must be less
|
||
than that at this node, so it cannot be bounded at the bottom and
|
||
we need not bother testing any further. */
|
||
|
||
if (node->left)
|
||
return false;
|
||
|
||
low_minus_one = fold_build2 (MINUS_EXPR, TREE_TYPE (node->low), node->low,
|
||
build_int_cst (TREE_TYPE (node->low), 1));
|
||
|
||
/* If the subtraction above overflowed, we can't verify anything.
|
||
Otherwise, look for a parent that tests our value - 1. */
|
||
|
||
if (!tree_int_cst_lt (low_minus_one, node->low))
|
||
return false;
|
||
|
||
for (pnode = node->parent; pnode; pnode = pnode->parent)
|
||
if (tree_int_cst_equal (low_minus_one, pnode->high))
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/* Search the parent sections of the case node tree
|
||
to see if a test for the upper bound of NODE would be redundant.
|
||
INDEX_TYPE is the type of the index expression.
|
||
|
||
The instructions to generate the case decision tree are
|
||
output in the same order as nodes are processed so it is
|
||
known that if a parent node checks the range of the current
|
||
node plus one that the current node is bounded at its upper
|
||
span. Thus the test would be redundant. */
|
||
|
||
static bool
|
||
node_has_high_bound (case_node_ptr node, tree index_type)
|
||
{
|
||
tree high_plus_one;
|
||
case_node_ptr pnode;
|
||
|
||
/* If there is no upper bound, obviously no test is needed. */
|
||
|
||
if (TYPE_MAX_VALUE (index_type) == NULL)
|
||
return true;
|
||
|
||
/* If the upper bound of this node is the highest value in the type
|
||
of the index expression, we need not test against it. */
|
||
|
||
if (tree_int_cst_equal (node->high, TYPE_MAX_VALUE (index_type)))
|
||
return true;
|
||
|
||
/* If this node has a right branch, the value at the right must be greater
|
||
than that at this node, so it cannot be bounded at the top and
|
||
we need not bother testing any further. */
|
||
|
||
if (node->right)
|
||
return false;
|
||
|
||
high_plus_one = fold_build2 (PLUS_EXPR, TREE_TYPE (node->high), node->high,
|
||
build_int_cst (TREE_TYPE (node->high), 1));
|
||
|
||
/* If the addition above overflowed, we can't verify anything.
|
||
Otherwise, look for a parent that tests our value + 1. */
|
||
|
||
if (!tree_int_cst_lt (node->high, high_plus_one))
|
||
return false;
|
||
|
||
for (pnode = node->parent; pnode; pnode = pnode->parent)
|
||
if (tree_int_cst_equal (high_plus_one, pnode->low))
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/* Search the parent sections of the
|
||
case node tree to see if both tests for the upper and lower
|
||
bounds of NODE would be redundant. */
|
||
|
||
static bool
|
||
node_is_bounded (case_node_ptr node, tree index_type)
|
||
{
|
||
return (node_has_low_bound (node, index_type)
|
||
&& node_has_high_bound (node, index_type));
|
||
}
|